Update to ruby/spec@b65d01f

186 files changed, 3865 insertions, 3248 deletions

diff --git a/spec/ruby/.rubocop.yml b/spec/ruby/.rubocop.yml
index 60b42cff7f..eab4c3c4a6 100644
--- a/spec/ruby/.rubocop.yml
+++ b/spec/ruby/.rubocop.yml
@@ -1,7 +1,7 @@
 inherit_from: .rubocop_todo.yml
 
 AllCops:
-  TargetRubyVersion: 2.5
+  TargetRubyVersion: 2.6
   DisplayCopNames: true
   Exclude:
     - command_line/fixtures/bad_syntax.rb
diff --git a/spec/ruby/CONTRIBUTING.md b/spec/ruby/CONTRIBUTING.md
index e470a811ff..30941677e0 100644
--- a/spec/ruby/CONTRIBUTING.md
+++ b/spec/ruby/CONTRIBUTING.md
@@ -178,7 +178,7 @@ First, file a bug at https://bugs.ruby-lang.org/.
 It is better to use a `ruby_version_is` guard if there was a release with the fix.
 
 ```ruby
-ruby_bug '#13669', ''...'2.5' do
+ruby_bug '#13669', ''...'2.7' do
   it "works like this" do
     # Specify the expected behavior here, not the bug
   end
diff --git a/spec/ruby/README.md b/spec/ruby/README.md
index c5b7d6fb6a..a12cc3f7d8 100644
--- a/spec/ruby/README.md
+++ b/spec/ruby/README.md
@@ -29,8 +29,8 @@ ruby/spec is known to be tested in these implementations for every commit:
 * [TruffleRuby](https://github.com/oracle/truffleruby/tree/master/spec/ruby)
 * [Opal](https://github.com/opal/opal/tree/master/spec)
 
-ruby/spec describes the behavior of Ruby 2.5 and more recent Ruby versions.
-More precisely, every latest stable MRI release should [pass](https://github.com/ruby/spec/actions/workflows/ci.yml) all specs of ruby/spec (2.5.x, 2.6.x, 2.7.x, etc), and those are tested in CI.
+ruby/spec describes the behavior of Ruby 2.6 and more recent Ruby versions.
+More precisely, every latest stable MRI release should [pass](https://github.com/ruby/spec/actions/workflows/ci.yml) all specs of ruby/spec (2.6.x, 2.7.x, 3.0.x, etc), and those are tested in CI.
 
 ### Synchronization with Ruby Implementations
 
@@ -57,6 +57,7 @@ For older specs try these commits:
 * Ruby 2.2.10 - [Suite](https://github.com/ruby/spec/commit/cbaa0e412270c944df0c2532fc500c920dba0e92) using [MSpec](https://github.com/ruby/mspec/commit/d84d7668449e96856c5f6bac8cb1526b6d357ce3)
 * Ruby 2.3.8 - [Suite](https://github.com/ruby/spec/commit/dc733114d8ae66a3368ba3a98422c50147a76ba5) using [MSpec](https://github.com/ruby/mspec/commit/4599bc195fb109f2a482a01c32a7d659518369ea)
 * Ruby 2.4.10 - [Suite](https://github.com/ruby/spec/commit/bce4f2b81d6c31db67cf4d023a0625ceadde59bd) using [MSpec](https://github.com/ruby/mspec/commit/e7eb8aa4c26495b7b461e687d950b96eb08b3ff2)
+* Ruby 2.5.9 - [Suite](https://github.com/ruby/spec/commit/c503335d3d9f6ec6ef24de60a0716c34af69b64f) using [MSpec](https://github.com/ruby/mspec/commit/0091e8a62e954717cd54641f935eaf1403692041)
 
 ### Running the specs
 
diff --git a/spec/ruby/command_line/feature_spec.rb b/spec/ruby/command_line/feature_spec.rb
index 16e106b37d..1a9ea925c9 100644
--- a/spec/ruby/command_line/feature_spec.rb
+++ b/spec/ruby/command_line/feature_spec.rb
@@ -1,6 +1,12 @@
 require_relative '../spec_helper'
 
 describe "The --enable and --disable flags" do
+  before :all do
+    # Since some specs disable reading RUBYOPT, we instead pass its contents as :options for those specs
+    rubyopt = [ENV["RUBYOPT"]]
+    rubyopt << ENV["#{RUBY_ENGINE.upcase}OPT"] unless RUBY_ENGINE == 'ruby'
+    @rubyopt = RUBY_ENGINE == "ruby" ? "" : rubyopt.compact.join(" ")
+  end
 
   it "can be used with gems" do
     ruby_exe("p defined?(Gem)", options: "--enable=gems").chomp.should == "\"constant\""
@@ -25,9 +31,9 @@ describe "The --enable and --disable flags" do
 
   it "can be used with rubyopt" do
     ruby_exe("p $VERBOSE", options: "--enable=rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "true"
-    ruby_exe("p $VERBOSE", options: "--disable=rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "false"
+    ruby_exe("p $VERBOSE", options: "#{@rubyopt} --disable=rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "false"
     ruby_exe("p $VERBOSE", options: "--enable-rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "true"
-    ruby_exe("p $VERBOSE", options: "--disable-rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "false"
+    ruby_exe("p $VERBOSE", options: "#{@rubyopt} --disable-rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "false"
   end
 
   it "can be used with frozen-string-literal" do
@@ -49,8 +55,8 @@ describe "The --enable and --disable flags" do
   it "can be used with all for disable" do
     e = "p [defined?(Gem), defined?(DidYouMean), $VERBOSE, 'foo'.frozen?]"
     env = {'RUBYOPT' => '-w'}
-    ruby_exe(e, options: "--disable=all", env: env).chomp.should == "[nil, nil, false, false]"
-    ruby_exe(e, options: "--disable-all", env: env).chomp.should == "[nil, nil, false, false]"
+    ruby_exe(e, options: "#{@rubyopt} --disable=all", env: env).chomp.should == "[nil, nil, false, false]"
+    ruby_exe(e, options: "#{@rubyopt} --disable-all", env: env).chomp.should == "[nil, nil, false, false]"
   end
 
   it "prints a warning for unknown features" do
diff --git a/spec/ruby/core/array/difference_spec.rb b/spec/ruby/core/array/difference_spec.rb
index a357657967..9f7d4c4a1a 100644
--- a/spec/ruby/core/array/difference_spec.rb
+++ b/spec/ruby/core/array/difference_spec.rb
@@ -2,23 +2,21 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/difference'
 
-ruby_version_is "2.6" do
-  describe "Array#difference" do
-    it_behaves_like :array_binary_difference, :difference
+describe "Array#difference" do
+  it_behaves_like :array_binary_difference, :difference
 
-    it "returns a copy when called without any parameter" do
-      x = [1, 2, 3, 2]
-      x.difference.should == x
-      x.difference.should_not equal x
-    end
+  it "returns a copy when called without any parameter" do
+    x = [1, 2, 3, 2]
+    x.difference.should == x
+    x.difference.should_not equal x
+  end
 
-    it "does not return subclass instances for Array subclasses" do
-      ArraySpecs::MyArray[1, 2, 3].difference.should be_an_instance_of(Array)
-    end
+  it "does not return subclass instances for Array subclasses" do
+    ArraySpecs::MyArray[1, 2, 3].difference.should be_an_instance_of(Array)
+  end
 
-    it "accepts multiple arguments" do
-      x = [1, 2, 3, 1]
-      x.difference([], [0, 1], [3, 4], [3]).should == [2]
-    end
+  it "accepts multiple arguments" do
+    x = [1, 2, 3, 1]
+    x.difference([], [0, 1], [3, 4], [3]).should == [2]
   end
 end
diff --git a/spec/ruby/core/array/element_set_spec.rb b/spec/ruby/core/array/element_set_spec.rb
index 07c64b919e..1e192c100f 100644
--- a/spec/ruby/core/array/element_set_spec.rb
+++ b/spec/ruby/core/array/element_set_spec.rb
@@ -445,41 +445,39 @@ describe "Array#[]= with [m..n]" do
   end
 end
 
-ruby_version_is "2.6" do
-  describe "Array#[]= with [m..]" do
-    it "just sets the section defined by range to nil even if the rhs is nil" do
-      a = [1, 2, 3, 4, 5]
-      a[eval("(2..)")] = nil
-      a.should == [1, 2, nil]
-    end
+describe "Array#[]= with [m..]" do
+  it "just sets the section defined by range to nil even if the rhs is nil" do
+    a = [1, 2, 3, 4, 5]
+    a[eval("(2..)")] = nil
+    a.should == [1, 2, nil]
+  end
 
-    it "just sets the section defined by range to nil if m and n < 0 and the rhs is nil" do
-      a = [1, 2, 3, 4, 5]
-      a[eval("(-3..)")] = nil
-      a.should == [1, 2, nil]
-    end
+  it "just sets the section defined by range to nil if m and n < 0 and the rhs is nil" do
+    a = [1, 2, 3, 4, 5]
+    a[eval("(-3..)")] = nil
+    a.should == [1, 2, nil]
+  end
 
-    it "replaces the section defined by range" do
-      a = [6, 5, 4, 3, 2, 1]
-      a[eval("(3...)")] = 9
-      a.should == [6, 5, 4, 9]
-      a[eval("(2..)")] = [7, 7, 7]
-      a.should == [6, 5, 7, 7, 7]
-    end
+  it "replaces the section defined by range" do
+    a = [6, 5, 4, 3, 2, 1]
+    a[eval("(3...)")] = 9
+    a.should == [6, 5, 4, 9]
+    a[eval("(2..)")] = [7, 7, 7]
+    a.should == [6, 5, 7, 7, 7]
+  end
 
-    it "replaces the section if m and n < 0" do
-      a = [1, 2, 3, 4, 5]
-      a[eval("(-3..)")] = [7, 8, 9]
-      a.should == [1, 2, 7, 8, 9]
-    end
+  it "replaces the section if m and n < 0" do
+    a = [1, 2, 3, 4, 5]
+    a[eval("(-3..)")] = [7, 8, 9]
+    a.should == [1, 2, 7, 8, 9]
+  end
 
-    it "inserts at the end if m > the array size" do
-      a = [1, 2, 3]
-      a[eval("(3..)")] = [4]
-      a.should == [1, 2, 3, 4]
-      a[eval("(5..)")] = [6]
-      a.should == [1, 2, 3, 4, nil, 6]
-    end
+  it "inserts at the end if m > the array size" do
+    a = [1, 2, 3]
+    a[eval("(3..)")] = [4]
+    a.should == [1, 2, 3, 4]
+    a[eval("(5..)")] = [6]
+    a.should == [1, 2, 3, 4, nil, 6]
   end
 end
 
diff --git a/spec/ruby/core/array/fill_spec.rb b/spec/ruby/core/array/fill_spec.rb
index 8f0814a5da..bfa8db551b 100644
--- a/spec/ruby/core/array/fill_spec.rb
+++ b/spec/ruby/core/array/fill_spec.rb
@@ -316,13 +316,11 @@ describe "Array#fill with (filler, range)" do
     -> { [].fill('a', obj..obj) }.should raise_error(TypeError)
   end
 
-  ruby_version_is "2.6" do
-    it "works with endless ranges" do
-      [1, 2, 3, 4].fill('x', eval("(1..)")).should == [1, 'x', 'x', 'x']
-      [1, 2, 3, 4].fill('x', eval("(3...)")).should == [1, 2, 3, 'x']
-      [1, 2, 3, 4].fill(eval("(1..)")) { |x| x + 2 }.should == [1, 3, 4, 5]
-      [1, 2, 3, 4].fill(eval("(3...)")) { |x| x + 2 }.should == [1, 2, 3, 5]
-    end
+  it "works with endless ranges" do
+    [1, 2, 3, 4].fill('x', eval("(1..)")).should == [1, 'x', 'x', 'x']
+    [1, 2, 3, 4].fill('x', eval("(3...)")).should == [1, 2, 3, 'x']
+    [1, 2, 3, 4].fill(eval("(1..)")) { |x| x + 2 }.should == [1, 3, 4, 5]
+    [1, 2, 3, 4].fill(eval("(3...)")) { |x| x + 2 }.should == [1, 2, 3, 5]
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/array/filter_spec.rb b/spec/ruby/core/array/filter_spec.rb
index ee4f71ca28..156ad14f9c 100644
--- a/spec/ruby/core/array/filter_spec.rb
+++ b/spec/ruby/core/array/filter_spec.rb
@@ -1,16 +1,14 @@
 require_relative '../../spec_helper'
 require_relative 'shared/select'
 
-ruby_version_is "2.6" do
-  describe "Array#filter" do
-    it_behaves_like :array_select, :filter
-  end
-
-  describe "Array#filter!" do
-    it "returns nil if no changes were made in the array" do
-      [1, 2, 3].filter! { true }.should be_nil
-    end
+describe "Array#filter" do
+  it_behaves_like :array_select, :filter
+end
 
-    it_behaves_like :keep_if, :filter!
+describe "Array#filter!" do
+  it "returns nil if no changes were made in the array" do
+    [1, 2, 3].filter! { true }.should be_nil
   end
+
+  it_behaves_like :keep_if, :filter!
 end
diff --git a/spec/ruby/core/array/shared/slice.rb b/spec/ruby/core/array/shared/slice.rb
index 6818badeda..19e1a3ee2b 100644
--- a/spec/ruby/core/array/shared/slice.rb
+++ b/spec/ruby/core/array/shared/slice.rb
@@ -521,18 +521,16 @@ describe :array_slice, shared: true do
     -> { "hello".send(@method, 0..bignum_value) }.should raise_error(RangeError)
   end
 
-  ruby_version_is "2.6" do
-    it "can accept endless ranges" do
-      a = [0, 1, 2, 3, 4, 5]
-      a.send(@method, eval("(2..)")).should == [2, 3, 4, 5]
-      a.send(@method, eval("(2...)")).should == [2, 3, 4, 5]
-      a.send(@method, eval("(-2..)")).should == [4, 5]
-      a.send(@method, eval("(-2...)")).should == [4, 5]
-      a.send(@method, eval("(9..)")).should == nil
-      a.send(@method, eval("(9...)")).should == nil
-      a.send(@method, eval("(-9..)")).should == nil
-      a.send(@method, eval("(-9...)")).should == nil
-    end
+  it "can accept endless ranges" do
+    a = [0, 1, 2, 3, 4, 5]
+    a.send(@method, eval("(2..)")).should == [2, 3, 4, 5]
+    a.send(@method, eval("(2...)")).should == [2, 3, 4, 5]
+    a.send(@method, eval("(-2..)")).should == [4, 5]
+    a.send(@method, eval("(-2...)")).should == [4, 5]
+    a.send(@method, eval("(9..)")).should == nil
+    a.send(@method, eval("(9...)")).should == nil
+    a.send(@method, eval("(-9..)")).should == nil
+    a.send(@method, eval("(-9...)")).should == nil
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/array/slice_spec.rb b/spec/ruby/core/array/slice_spec.rb
index 2f98df9488..8c276f9084 100644
--- a/spec/ruby/core/array/slice_spec.rb
+++ b/spec/ruby/core/array/slice_spec.rb
@@ -154,24 +154,22 @@ describe "Array#slice!" do
     -> { ArraySpecs.frozen_array.slice!(0, 0) }.should raise_error(FrozenError)
   end
 
-  ruby_version_is "2.6" do
-    it "works with endless ranges" do
-      a = [1, 2, 3]
-      a.slice!(eval("(1..)")).should == [2, 3]
-      a.should == [1]
-
-      a = [1, 2, 3]
-      a.slice!(eval("(2...)")).should == [3]
-      a.should == [1, 2]
-
-      a = [1, 2, 3]
-      a.slice!(eval("(-2..)")).should == [2, 3]
-      a.should == [1]
-
-      a = [1, 2, 3]
-      a.slice!(eval("(-1...)")).should == [3]
-      a.should == [1, 2]
-    end
+  it "works with endless ranges" do
+    a = [1, 2, 3]
+    a.slice!(eval("(1..)")).should == [2, 3]
+    a.should == [1]
+
+    a = [1, 2, 3]
+    a.slice!(eval("(2...)")).should == [3]
+    a.should == [1, 2]
+
+    a = [1, 2, 3]
+    a.slice!(eval("(-2..)")).should == [2, 3]
+    a.should == [1]
+
+    a = [1, 2, 3]
+    a.slice!(eval("(-1...)")).should == [3]
+    a.should == [1, 2]
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/array/to_h_spec.rb b/spec/ruby/core/array/to_h_spec.rb
index 46a79ba58b..f5a7e546e6 100644
--- a/spec/ruby/core/array/to_h_spec.rb
+++ b/spec/ruby/core/array/to_h_spec.rb
@@ -39,43 +39,41 @@ describe "Array#to_h" do
     [[:a, 1], [:b, 2]].to_h[:c].should be_nil
   end
 
-  ruby_version_is "2.6" do
-    context "with block" do
-      it "converts [key, value] pairs returned by the block to a Hash" do
-        [:a, :b].to_h { |k| [k, k.to_s] }.should == { a: 'a', b: 'b' }
-      end
-
-      it "raises ArgumentError if block returns longer or shorter array" do
-        -> do
-          [:a, :b].to_h { |k| [k, k.to_s, 1] }
-        end.should raise_error(ArgumentError, /wrong array length at 0/)
-
-        -> do
-          [:a, :b].to_h { |k| [k] }
-        end.should raise_error(ArgumentError, /wrong array length at 0/)
-      end
-
-      it "raises TypeError if block returns something other than Array" do
-        -> do
-          [:a, :b].to_h { |k| "not-array" }
-        end.should raise_error(TypeError, /wrong element type String at 0/)
-      end
-
-      it "coerces returned pair to Array with #to_ary" do
-        x = mock('x')
-        x.stub!(:to_ary).and_return([:b, 'b'])
-
-        [:a].to_h { |k| x }.should == { :b => 'b' }
-      end
-
-      it "does not coerce returned pair to Array with #to_a" do
-        x = mock('x')
-        x.stub!(:to_a).and_return([:b, 'b'])
-
-        -> do
-          [:a].to_h { |k| x }
-        end.should raise_error(TypeError, /wrong element type MockObject at 0/)
-      end
+  context "with block" do
+    it "converts [key, value] pairs returned by the block to a Hash" do
+      [:a, :b].to_h { |k| [k, k.to_s] }.should == { a: 'a', b: 'b' }
+    end
+
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        [:a, :b].to_h { |k| [k, k.to_s, 1] }
+      end.should raise_error(ArgumentError, /wrong array length at 0/)
+
+      -> do
+        [:a, :b].to_h { |k| [k] }
+      end.should raise_error(ArgumentError, /wrong array length at 0/)
+    end
+
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        [:a, :b].to_h { |k| "not-array" }
+      end.should raise_error(TypeError, /wrong element type String at 0/)
+    end
+
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
+
+      [:a].to_h { |k| x }.should == { :b => 'b' }
+    end
+
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
+
+      -> do
+        [:a].to_h { |k| x }
+      end.should raise_error(TypeError, /wrong element type MockObject at 0/)
     end
   end
 end
diff --git a/spec/ruby/core/array/union_spec.rb b/spec/ruby/core/array/union_spec.rb
index 1dca47696d..ba2cc0d6b7 100644
--- a/spec/ruby/core/array/union_spec.rb
+++ b/spec/ruby/core/array/union_spec.rb
@@ -6,22 +6,20 @@ describe "Array#|" do
   it_behaves_like :array_binary_union, :|
 end
 
-ruby_version_is "2.6" do
-  describe "Array#union" do
-    it_behaves_like :array_binary_union, :union
+describe "Array#union" do
+  it_behaves_like :array_binary_union, :union
 
-    it "returns unique elements when given no argument" do
-      x = [1, 2, 3, 2]
-      x.union.should == [1, 2, 3]
-    end
+  it "returns unique elements when given no argument" do
+    x = [1, 2, 3, 2]
+    x.union.should == [1, 2, 3]
+  end
 
-    it "does not return subclass instances for Array subclasses" do
-      ArraySpecs::MyArray[1, 2, 3].union.should be_an_instance_of(Array)
-    end
+  it "does not return subclass instances for Array subclasses" do
+    ArraySpecs::MyArray[1, 2, 3].union.should be_an_instance_of(Array)
+  end
 
-    it "accepts multiple arguments" do
-      x = [1, 2, 3]
-      x.union(x, x, x, x, [3, 4], x).should == [1, 2, 3, 4]
-    end
+  it "accepts multiple arguments" do
+    x = [1, 2, 3]
+    x.union(x, x, x, x, [3, 4], x).should == [1, 2, 3, 4]
   end
 end
diff --git a/spec/ruby/core/array/values_at_spec.rb b/spec/ruby/core/array/values_at_spec.rb
index 019152c51c..f1522e0bfe 100644
--- a/spec/ruby/core/array/values_at_spec.rb
+++ b/spec/ruby/core/array/values_at_spec.rb
@@ -61,11 +61,9 @@ describe "Array#values_at" do
     ArraySpecs::MyArray[1, 2, 3].values_at(0, 1..2, 1).should be_an_instance_of(Array)
   end
 
-  ruby_version_is "2.6" do
-    it "works when given endless ranges" do
-      [1, 2, 3, 4].values_at(eval("(1..)")).should == [2, 3, 4]
-      [1, 2, 3, 4].values_at(eval("(3...)")).should == [4]
-    end
+  it "works when given endless ranges" do
+    [1, 2, 3, 4].values_at(eval("(1..)")).should == [2, 3, 4]
+    [1, 2, 3, 4].values_at(eval("(3...)")).should == [4]
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/binding/source_location_spec.rb b/spec/ruby/core/binding/source_location_spec.rb
index e562bc65c8..d439c3e399 100644
--- a/spec/ruby/core/binding/source_location_spec.rb
+++ b/spec/ruby/core/binding/source_location_spec.rb
@@ -1,11 +1,9 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/location'
 
-ruby_version_is "2.6" do
-  describe "Binding#source_location" do
-    it "returns an [file, line] pair" do
-      b = BindingSpecs::LocationMethod::TEST_BINDING
-      b.source_location.should == [BindingSpecs::LocationMethod::FILE_PATH, 4]
-    end
+describe "Binding#source_location" do
+  it "returns an [file, line] pair" do
+    b = BindingSpecs::LocationMethod::TEST_BINDING
+    b.source_location.should == [BindingSpecs::LocationMethod::FILE_PATH, 4]
   end
 end
diff --git a/spec/ruby/core/dir/children_spec.rb b/spec/ruby/core/dir/children_spec.rb
index f890f54eb4..986c8f38c0 100644
--- a/spec/ruby/core/dir/children_spec.rb
+++ b/spec/ruby/core/dir/children_spec.rb
@@ -69,76 +69,74 @@ describe "Dir.children" do
   end
 end
 
-ruby_version_is "2.6" do
-  describe "Dir#children" do
-    before :all do
-      DirSpecs.create_mock_dirs
-    end
+describe "Dir#children" do
+  before :all do
+    DirSpecs.create_mock_dirs
+  end
 
-    before :each do
-      @internal = Encoding.default_internal
-    end
+  before :each do
+    @internal = Encoding.default_internal
+  end
 
-    after :all do
-      DirSpecs.delete_mock_dirs
-    end
+  after :all do
+    DirSpecs.delete_mock_dirs
+  end
 
-    after :each do
-      Encoding.default_internal = @internal
-      @dir.close if @dir
-    end
+  after :each do
+    Encoding.default_internal = @internal
+    @dir.close if @dir
+  end
 
-    it "returns an Array of filenames in an existing directory including dotfiles" do
-      @dir = Dir.new(DirSpecs.mock_dir)
-      a = @dir.children.sort
-      @dir.close
+  it "returns an Array of filenames in an existing directory including dotfiles" do
+    @dir = Dir.new(DirSpecs.mock_dir)
+    a = @dir.children.sort
+    @dir.close
 
-      a.should == DirSpecs.expected_paths - %w[. ..]
+    a.should == DirSpecs.expected_paths - %w[. ..]
 
-      @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested")
-      a = @dir.children.sort
-      a.should == %w|.dotfile.ext directory|
-    end
+    @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested")
+    a = @dir.children.sort
+    a.should == %w|.dotfile.ext directory|
+  end
 
-    it "accepts an encoding keyword for the encoding of the entries" do
-      @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8")
-      dirs = @dir.to_a.sort
-      dirs.each { |d| d.encoding.should == Encoding::UTF_8 }
-    end
+  it "accepts an encoding keyword for the encoding of the entries" do
+    @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8")
+    dirs = @dir.to_a.sort
+    dirs.each { |d| d.encoding.should == Encoding::UTF_8 }
+  end
 
-    ruby_version_is ""..."2.7" do
-      it "accepts nil options" do
-        @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested", nil)
-        dirs = @dir.to_a.sort
-        dirs.each { |d| d.encoding.should == Encoding.find("filesystem") }
-      end
+  ruby_version_is ""..."2.7" do
+    it "accepts nil options" do
+      @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested", nil)
+      dirs = @dir.to_a.sort
+      dirs.each { |d| d.encoding.should == Encoding.find("filesystem") }
     end
+  end
 
-    it "returns children encoded with the filesystem encoding by default" do
-      # This spec depends on the locale not being US-ASCII because if it is, the
-      # children that are not ascii_only? will be BINARY encoded.
-      @dir = Dir.new(File.join(DirSpecs.mock_dir, 'special'))
-      children = @dir.children.sort
-      encoding = Encoding.find("filesystem")
-      encoding = Encoding::BINARY if encoding == Encoding::US_ASCII
-      platform_is_not :windows do
-        children.should include("こんにちは.txt".force_encoding(encoding))
-      end
-      children.first.encoding.should equal(Encoding.find("filesystem"))
+  it "returns children encoded with the filesystem encoding by default" do
+    # This spec depends on the locale not being US-ASCII because if it is, the
+    # children that are not ascii_only? will be BINARY encoded.
+    @dir = Dir.new(File.join(DirSpecs.mock_dir, 'special'))
+    children = @dir.children.sort
+    encoding = Encoding.find("filesystem")
+    encoding = Encoding::BINARY if encoding == Encoding::US_ASCII
+    platform_is_not :windows do
+      children.should include("こんにちは.txt".force_encoding(encoding))
     end
+    children.first.encoding.should equal(Encoding.find("filesystem"))
+  end
 
-    it "returns children encoded with the specified encoding" do
-      path = File.join(DirSpecs.mock_dir, 'special')
-      @dir = Dir.new(path, encoding: "euc-jp")
-      children = @dir.children.sort
-      children.first.encoding.should equal(Encoding::EUC_JP)
-    end
+  it "returns children encoded with the specified encoding" do
+    path = File.join(DirSpecs.mock_dir, 'special')
+    @dir = Dir.new(path, encoding: "euc-jp")
+    children = @dir.children.sort
+    children.first.encoding.should equal(Encoding::EUC_JP)
+  end
 
-    it "returns children transcoded to the default internal encoding" do
-      Encoding.default_internal = Encoding::EUC_KR
-      @dir = Dir.new(File.join(DirSpecs.mock_dir, 'special'))
-      children = @dir.children.sort
-      children.first.encoding.should equal(Encoding::EUC_KR)
-    end
+  it "returns children transcoded to the default internal encoding" do
+    Encoding.default_internal = Encoding::EUC_KR
+    @dir = Dir.new(File.join(DirSpecs.mock_dir, 'special'))
+    children = @dir.children.sort
+    children.first.encoding.should equal(Encoding::EUC_KR)
   end
 end
diff --git a/spec/ruby/core/dir/each_child_spec.rb b/spec/ruby/core/dir/each_child_spec.rb
index 684f42acc0..f7980991e5 100644
--- a/spec/ruby/core/dir/each_child_spec.rb
+++ b/spec/ruby/core/dir/each_child_spec.rb
@@ -62,52 +62,50 @@ describe "Dir.each_child" do
   end
 end
 
-ruby_version_is "2.6" do
-  describe "Dir#each_child" do
-    before :all do
-      DirSpecs.create_mock_dirs
-    end
+describe "Dir#each_child" do
+  before :all do
+    DirSpecs.create_mock_dirs
+  end
 
-    after :all do
-      DirSpecs.delete_mock_dirs
-    end
+  after :all do
+    DirSpecs.delete_mock_dirs
+  end
 
-    after :each do
-      @dir.close if @dir
-    end
+  after :each do
+    @dir.close if @dir
+  end
 
-    it "yields all names in an existing directory to the provided block" do
-      a, b = [], []
-      @dir = Dir.new(DirSpecs.mock_dir)
-      @dir2 = Dir.new("#{DirSpecs.mock_dir}/deeply/nested")
+  it "yields all names in an existing directory to the provided block" do
+    a, b = [], []
+    @dir = Dir.new(DirSpecs.mock_dir)
+    @dir2 = Dir.new("#{DirSpecs.mock_dir}/deeply/nested")
 
-      @dir.each_child { |f| a << f }
-      @dir2.each_child { |f| b << f }
-      @dir2.close
+    @dir.each_child { |f| a << f }
+    @dir2.each_child { |f| b << f }
+    @dir2.close
 
-      a.sort.should == DirSpecs.expected_paths - %w|. ..|
-      b.sort.should == %w|.dotfile.ext directory|
-    end
+    a.sort.should == DirSpecs.expected_paths - %w|. ..|
+    b.sort.should == %w|.dotfile.ext directory|
+  end
 
-    it "returns self when successful" do
-      @dir = Dir.new(DirSpecs.mock_dir)
-      @dir.each_child { |f| f }.should == @dir
-    end
+  it "returns self when successful" do
+    @dir = Dir.new(DirSpecs.mock_dir)
+    @dir.each_child { |f| f }.should == @dir
+  end
 
-    describe "when no block is given" do
-      it "returns an Enumerator" do
-        @dir = Dir.new(DirSpecs.mock_dir)
+  describe "when no block is given" do
+    it "returns an Enumerator" do
+      @dir = Dir.new(DirSpecs.mock_dir)
 
-        @dir.each_child.should be_an_instance_of(Enumerator)
-        @dir.each_child.to_a.sort.should == DirSpecs.expected_paths - %w|. ..|
-      end
+      @dir.each_child.should be_an_instance_of(Enumerator)
+      @dir.each_child.to_a.sort.should == DirSpecs.expected_paths - %w|. ..|
+    end
 
-      describe "returned Enumerator" do
-        describe "size" do
-          it "should return nil" do
-            @dir = Dir.new(DirSpecs.mock_dir)
-            @dir.each_child.size.should == nil
-          end
+    describe "returned Enumerator" do
+      describe "size" do
+        it "should return nil" do
+          @dir = Dir.new(DirSpecs.mock_dir)
+          @dir.each_child.size.should == nil
         end
       end
     end
diff --git a/spec/ruby/core/dir/glob_spec.rb b/spec/ruby/core/dir/glob_spec.rb
index 61553ab0b1..6533c9b65a 100644
--- a/spec/ruby/core/dir/glob_spec.rb
+++ b/spec/ruby/core/dir/glob_spec.rb
@@ -29,6 +29,23 @@ describe "Dir.glob" do
                %w!file_one.ext file_two.ext!
   end
 
+  it 'returns matching file paths when supplied :base keyword argument' do
+    dir = tmp('dir_glob_base')
+    file_1 = "#{dir}/lib/bloop.rb"
+    file_2 = "#{dir}/lib/soup.rb"
+    file_3 = "#{dir}/lib/mismatched_file_type.txt"
+    file_4 = "#{dir}/mismatched_directory.rb"
+
+    touch file_1
+    touch file_2
+    touch file_3
+    touch file_4
+
+    Dir.glob('**/*.rb', base: "#{dir}/lib").sort.should == ["bloop.rb", "soup.rb"].sort
+  ensure
+    rm_r dir
+  end
+
   it "calls #to_path to convert multiple patterns" do
     pat1 = mock('file_one.ext')
     pat1.should_receive(:to_path).and_return('file_one.ext')
@@ -133,6 +150,14 @@ describe "Dir.glob" do
     Dir.glob('{deeply/**/,subdir_two/*}').sort.should == expected
   end
 
+  it "preserves multiple /s before a **" do
+    expected = %w[
+      deeply//nested/directory/structure
+    ]
+
+    Dir.glob('{deeply//**/structure}').sort.should == expected
+  end
+
   it "accepts a block and yields it with each elements" do
     ary = []
     ret = Dir.glob(["file_o*", "file_t*"]) { |t| ary << t }
diff --git a/spec/ruby/core/dir/shared/glob.rb b/spec/ruby/core/dir/shared/glob.rb
index c35f7d71ca..ae5c2a114b 100644
--- a/spec/ruby/core/dir/shared/glob.rb
+++ b/spec/ruby/core/dir/shared/glob.rb
@@ -23,14 +23,7 @@ describe :dir_glob, shared: true do
     Dir.send(@method, obj).should == %w[file_one.ext]
   end
 
-  ruby_version_is ""..."2.6" do
-    it "splits the string on \\0 if there is only one string given" do
-      Dir.send(@method, "file_o*\0file_t*").should ==
-        %w!file_one.ext file_two.ext!
-    end
-  end
-
-  ruby_version_is "2.6"..."2.7" do
+  ruby_version_is ""..."2.7" do
     it "splits the string on \\0 if there is only one string given and warns" do
       -> {
         Dir.send(@method, "file_o*\0file_t*").should ==
@@ -205,6 +198,14 @@ describe :dir_glob, shared: true do
     Dir.send(@method, '**/').sort.should == expected
   end
 
+  it "recursively matches any subdirectories except './' or '../' with '**/' from the base directory if that is specified" do
+    expected = %w[
+      nested/directory
+    ]
+
+    Dir.send(@method, '**/*ory', base: 'deeply').sort.should == expected
+  end
+
   ruby_version_is ''...'3.1' do
     it "recursively matches any subdirectories including ./ and ../ with '.**/'" do
       Dir.chdir("#{DirSpecs.mock_dir}/subdir_one") do
diff --git a/spec/ruby/core/enumerable/all_spec.rb b/spec/ruby/core/enumerable/all_spec.rb
index 7e9726fe87..b782f94a3e 100644
--- a/spec/ruby/core/enumerable/all_spec.rb
+++ b/spec/ruby/core/enumerable/all_spec.rb
@@ -132,14 +132,6 @@ describe "Enumerable#all?" do
     end
 
     # may raise an exception in future versions
-    ruby_version_is ""..."2.6" do
-      it "ignores block" do
-        @enum2.all?(NilClass) { raise }.should == false
-        [1, 2, nil].all?(NilClass) { raise }.should == false
-        {a: 1}.all?(Array) { raise }.should == true
-      end
-    end
-
     it "always returns true on empty enumeration" do
       @empty.all?(Integer).should == true
       [].all?(Integer).should == true
diff --git a/spec/ruby/core/enumerable/any_spec.rb b/spec/ruby/core/enumerable/any_spec.rb
index 64e3159963..636b1fa450 100644
--- a/spec/ruby/core/enumerable/any_spec.rb
+++ b/spec/ruby/core/enumerable/any_spec.rb
@@ -146,14 +146,6 @@ describe "Enumerable#any?" do
     end
 
     # may raise an exception in future versions
-    ruby_version_is ""..."2.6" do
-      it "ignores block" do
-        @enum2.any?(NilClass) { raise }.should == true
-        [1, 2, nil].any?(NilClass) { raise }.should == true
-        {a: 1}.any?(Array) { raise }.should == true
-      end
-    end
-
     it "always returns false on empty enumeration" do
       @empty.any?(Integer).should == false
       [].any?(Integer).should == false
diff --git a/spec/ruby/core/enumerable/chain_spec.rb b/spec/ruby/core/enumerable/chain_spec.rb
index 85c0c03603..5e2105d294 100644
--- a/spec/ruby/core/enumerable/chain_spec.rb
+++ b/spec/ruby/core/enumerable/chain_spec.rb
@@ -1,25 +1,23 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-ruby_version_is "2.6" do
-  describe "Enumerable#chain" do
-    before :each do
-      ScratchPad.record []
-    end
+describe "Enumerable#chain" do
+  before :each do
+    ScratchPad.record []
+  end
 
-    it "returns a chain of self and provided enumerables" do
-      one = EnumerableSpecs::Numerous.new(1)
-      two = EnumerableSpecs::Numerous.new(2, 3)
-      three = EnumerableSpecs::Numerous.new(4, 5, 6)
+  it "returns a chain of self and provided enumerables" do
+    one = EnumerableSpecs::Numerous.new(1)
+    two = EnumerableSpecs::Numerous.new(2, 3)
+    three = EnumerableSpecs::Numerous.new(4, 5, 6)
 
-      chain = one.chain(two, three)
+    chain = one.chain(two, three)
 
-      chain.each { |item| ScratchPad << item }
-      ScratchPad.recorded.should == [1, 2, 3, 4, 5, 6]
-    end
+    chain.each { |item| ScratchPad << item }
+    ScratchPad.recorded.should == [1, 2, 3, 4, 5, 6]
+  end
 
-    it "returns an Enumerator::Chain if given a block" do
-      EnumerableSpecs::Numerous.new.chain.should be_an_instance_of(Enumerator::Chain)
-    end
+  it "returns an Enumerator::Chain if given a block" do
+    EnumerableSpecs::Numerous.new.chain.should be_an_instance_of(Enumerator::Chain)
   end
 end
diff --git a/spec/ruby/core/enumerable/filter_spec.rb b/spec/ruby/core/enumerable/filter_spec.rb
index f2dc7a7b71..7e4f8c0b50 100644
--- a/spec/ruby/core/enumerable/filter_spec.rb
+++ b/spec/ruby/core/enumerable/filter_spec.rb
@@ -2,8 +2,6 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/find_all'
 
-ruby_version_is "2.6" do
-  describe "Enumerable#filter" do
-    it_behaves_like(:enumerable_find_all , :filter)
-  end
+describe "Enumerable#filter" do
+  it_behaves_like(:enumerable_find_all , :filter)
 end
diff --git a/spec/ruby/core/enumerable/none_spec.rb b/spec/ruby/core/enumerable/none_spec.rb
index ec48eaf0a7..b898d00063 100644
--- a/spec/ruby/core/enumerable/none_spec.rb
+++ b/spec/ruby/core/enumerable/none_spec.rb
@@ -101,14 +101,6 @@ describe "Enumerable#none?" do
     end
 
     # may raise an exception in future versions
-    ruby_version_is ""..."2.6" do
-      it "ignores block" do
-        @enum2.none?(Integer) { raise }.should == true
-        [1, 2, nil].none?(TrueClass) { raise }.should == true
-        {a: 1}.none?(Hash) { raise }.should == true
-      end
-    end
-
     it "always returns true on empty enumeration" do
       @empty.none?(Integer).should == true
       [].none?(Integer).should == true
diff --git a/spec/ruby/core/enumerable/one_spec.rb b/spec/ruby/core/enumerable/one_spec.rb
index 6489c84742..d54dd4a527 100644
--- a/spec/ruby/core/enumerable/one_spec.rb
+++ b/spec/ruby/core/enumerable/one_spec.rb
@@ -92,14 +92,6 @@ describe "Enumerable#one?" do
     end
 
     # may raise an exception in future versions
-    ruby_version_is ""..."2.6" do
-      it "ignores block" do
-        @enum2.one?(NilClass) { raise }.should == true
-        [1, 2, nil].one?(NilClass) { raise }.should == true
-        {a: 1}.one?(Array) { raise }.should == true
-      end
-    end
-
     it "always returns false on empty enumeration" do
       @empty.one?(Integer).should == false
       [].one?(Integer).should == false
diff --git a/spec/ruby/core/enumerable/to_h_spec.rb b/spec/ruby/core/enumerable/to_h_spec.rb
index 63bfdf19af..0489134552 100644
--- a/spec/ruby/core/enumerable/to_h_spec.rb
+++ b/spec/ruby/core/enumerable/to_h_spec.rb
@@ -44,47 +44,45 @@ describe "Enumerable#to_h" do
     -> { enum.to_h }.should raise_error(ArgumentError)
   end
 
-  ruby_version_is "2.6" do
-    context "with block" do
-      before do
-        @enum = EnumerableSpecs::EachDefiner.new(:a, :b)
-      end
-
-      it "converts [key, value] pairs returned by the block to a hash" do
-        @enum.to_h { |k| [k, k.to_s] }.should == { a: 'a', b: 'b' }
-      end
-
-      it "raises ArgumentError if block returns longer or shorter array" do
-        -> do
-          @enum.to_h { |k| [k, k.to_s, 1] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-
-        -> do
-          @enum.to_h { |k| [k] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-      end
-
-      it "raises TypeError if block returns something other than Array" do
-        -> do
-          @enum.to_h { |k| "not-array" }
-        end.should raise_error(TypeError, /wrong element type String/)
-      end
-
-      it "coerces returned pair to Array with #to_ary" do
-        x = mock('x')
-        x.stub!(:to_ary).and_return([:b, 'b'])
-
-        @enum.to_h { |k| x }.should == { :b => 'b' }
-      end
-
-      it "does not coerce returned pair to Array with #to_a" do
-        x = mock('x')
-        x.stub!(:to_a).and_return([:b, 'b'])
-
-        -> do
-          @enum.to_h { |k| x }
-        end.should raise_error(TypeError, /wrong element type MockObject/)
-      end
+  context "with block" do
+    before do
+      @enum = EnumerableSpecs::EachDefiner.new(:a, :b)
+    end
+
+    it "converts [key, value] pairs returned by the block to a hash" do
+      @enum.to_h { |k| [k, k.to_s] }.should == { a: 'a', b: 'b' }
+    end
+
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        @enum.to_h { |k| [k, k.to_s, 1] }
+      end.should raise_error(ArgumentError, /element has wrong array length/)
+
+      -> do
+        @enum.to_h { |k| [k] }
+      end.should raise_error(ArgumentError, /element has wrong array length/)
+    end
+
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        @enum.to_h { |k| "not-array" }
+      end.should raise_error(TypeError, /wrong element type String/)
+    end
+
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
+
+      @enum.to_h { |k| x }.should == { :b => 'b' }
+    end
+
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
+
+      -> do
+        @enum.to_h { |k| x }
+      end.should raise_error(TypeError, /wrong element type MockObject/)
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/begin_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/begin_spec.rb
index c8d91ebaec..bed30c546d 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/begin_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/begin_spec.rb
@@ -1,11 +1,9 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#begin" do
-    it "returns the begin of the sequence" do
-      1.step(10).begin.should == 1
-      (1..10).step.begin.should == 1
-      (1...10).step.begin.should == 1
-    end
+describe "Enumerator::ArithmeticSequence#begin" do
+  it "returns the begin of the sequence" do
+    1.step(10).begin.should == 1
+    (1..10).step.begin.should == 1
+    (1...10).step.begin.should == 1
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/each_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/each_spec.rb
index d7edf3a21f..d4fff3e01f 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/each_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/each_spec.rb
@@ -1,19 +1,17 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#each" do
-    before :each do
-      ScratchPad.record []
-      @seq = 1.step(10, 4)
-    end
+describe "Enumerator::ArithmeticSequence#each" do
+  before :each do
+    ScratchPad.record []
+    @seq = 1.step(10, 4)
+  end
 
-    it "calls given block on each item of the sequence" do
-      @seq.each { |item| ScratchPad << item }
-      ScratchPad.recorded.should == [1, 5, 9]
-    end
+  it "calls given block on each item of the sequence" do
+    @seq.each { |item| ScratchPad << item }
+    ScratchPad.recorded.should == [1, 5, 9]
+  end
 
-    it "returns self" do
-      @seq.each { |item| }.should equal(@seq)
-    end
+  it "returns self" do
+    @seq.each { |item| }.should equal(@seq)
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/end_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/end_spec.rb
index 5a436e8167..29e6e105cf 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/end_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/end_spec.rb
@@ -1,11 +1,9 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#end" do
-    it "returns the end of the sequence" do
-      1.step(10).end.should == 10
-      (1..10).step.end.should == 10
-      (1...10).step(17).end.should == 10
-    end
+describe "Enumerator::ArithmeticSequence#end" do
+  it "returns the end of the sequence" do
+    1.step(10).end.should == 10
+    (1..10).step.end.should == 10
+    (1...10).step(17).end.should == 10
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/eq_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/eq_spec.rb
index 7895f98047..77eed02d8b 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/eq_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/eq_spec.rb
@@ -1,20 +1,18 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#==" do
-    it "returns true if begin, end, step and exclude_end? are equal" do
-      1.step(10).should == 1.step(10)
-      1.step(10, 5).should == 1.step(10, 5)
+describe "Enumerator::ArithmeticSequence#==" do
+  it "returns true if begin, end, step and exclude_end? are equal" do
+    1.step(10).should == 1.step(10)
+    1.step(10, 5).should == 1.step(10, 5)
 
-      (1..10).step.should == (1..10).step
-      (1...10).step(8).should == (1...10).step(8)
+    (1..10).step.should == (1..10).step
+    (1...10).step(8).should == (1...10).step(8)
 
-      # both have exclude_end? == false
-      (1..10).step(100).should == 1.step(10, 100)
+    # both have exclude_end? == false
+    (1..10).step(100).should == 1.step(10, 100)
 
-      ((1..10).step == (1..11).step).should == false
-      ((1..10).step == (1...10).step).should == false
-      ((1..10).step == (1..10).step(2)).should == false
-    end
+    ((1..10).step == (1..11).step).should == false
+    ((1..10).step == (1...10).step).should == false
+    ((1..10).step == (1..10).step(2)).should == false
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/exclude_end_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/exclude_end_spec.rb
index 5be189e993..021fe7d90f 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/exclude_end_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/exclude_end_spec.rb
@@ -1,19 +1,17 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#exclude_end?" do
-    context "when created using Numeric#step" do
-      it "always returns false" do
-        1.step(10).should_not.exclude_end?
-        10.step(1).should_not.exclude_end?
-      end
+describe "Enumerator::ArithmeticSequence#exclude_end?" do
+  context "when created using Numeric#step" do
+    it "always returns false" do
+      1.step(10).should_not.exclude_end?
+      10.step(1).should_not.exclude_end?
     end
+  end
 
-    context "when created using Range#step" do
-      it "mirrors range.exclude_end?" do
-        (1...10).step.should.exclude_end?
-        (1..10).step.should_not.exclude_end?
-      end
+  context "when created using Range#step" do
+    it "mirrors range.exclude_end?" do
+      (1...10).step.should.exclude_end?
+      (1..10).step.should_not.exclude_end?
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/first_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/first_spec.rb
index 43c520d1f0..ccd02be020 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/first_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/first_spec.rb
@@ -1,11 +1,9 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#first" do
-    it "returns the first element of the sequence" do
-      1.step(10).first.should == 1
-      (1..10).step.first.should == 1
-      (1...10).step.first.should == 1
-    end
+describe "Enumerator::ArithmeticSequence#first" do
+  it "returns the first element of the sequence" do
+    1.step(10).first.should == 1
+    (1..10).step.first.should == 1
+    (1...10).step.first.should == 1
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/hash_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/hash_spec.rb
index 236f845f41..bdb308074b 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/hash_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/hash_spec.rb
@@ -1,22 +1,20 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#hash" do
-    it "is based on begin, end, step and exclude_end?" do
-      1.step(10).hash.should be_an_instance_of(Integer)
+describe "Enumerator::ArithmeticSequence#hash" do
+  it "is based on begin, end, step and exclude_end?" do
+    1.step(10).hash.should be_an_instance_of(Integer)
 
-      1.step(10).hash.should == 1.step(10).hash
-      1.step(10, 5).hash.should == 1.step(10, 5).hash
+    1.step(10).hash.should == 1.step(10).hash
+    1.step(10, 5).hash.should == 1.step(10, 5).hash
 
-      (1..10).step.hash.should == (1..10).step.hash
-      (1...10).step(8).hash.should == (1...10).step(8).hash
+    (1..10).step.hash.should == (1..10).step.hash
+    (1...10).step(8).hash.should == (1...10).step(8).hash
 
-      # both have exclude_end? == false
-      (1..10).step(100).hash.should == 1.step(10, 100).hash
+    # both have exclude_end? == false
+    (1..10).step(100).hash.should == 1.step(10, 100).hash
 
-      ((1..10).step.hash == (1..11).step.hash).should == false
-      ((1..10).step.hash == (1...10).step.hash).should == false
-      ((1..10).step.hash == (1..10).step(2).hash).should == false
-    end
+    ((1..10).step.hash == (1..11).step.hash).should == false
+    ((1..10).step.hash == (1...10).step.hash).should == false
+    ((1..10).step.hash == (1..10).step(2).hash).should == false
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/inspect_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/inspect_spec.rb
index 21e64a6b58..b73b49d272 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/inspect_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/inspect_spec.rb
@@ -1,22 +1,20 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#inspect" do
-    context 'when Numeric#step is used' do
-      it "returns '(begin.step(end{, step}))'" do
-        1.step(10).inspect.should == "(1.step(10))"
-        1.step(10, 3).inspect.should == "(1.step(10, 3))"
-      end
+describe "Enumerator::ArithmeticSequence#inspect" do
+  context 'when Numeric#step is used' do
+    it "returns '(begin.step(end{, step}))'" do
+      1.step(10).inspect.should == "(1.step(10))"
+      1.step(10, 3).inspect.should == "(1.step(10, 3))"
     end
+  end
 
-    context 'when Range#step is used' do
-      it "returns '((range).step{(step)})'" do
-        (1..10).step.inspect.should == "((1..10).step)"
-        (1..10).step(3).inspect.should == "((1..10).step(3))"
+  context 'when Range#step is used' do
+    it "returns '((range).step{(step)})'" do
+      (1..10).step.inspect.should == "((1..10).step)"
+      (1..10).step(3).inspect.should == "((1..10).step(3))"
 
-        (1...10).step.inspect.should == "((1...10).step)"
-        (1...10).step(3).inspect.should == "((1...10).step(3))"
-      end
+      (1...10).step.inspect.should == "((1...10).step)"
+      (1...10).step(3).inspect.should == "((1...10).step(3))"
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/last_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/last_spec.rb
index ebb20090fc..31f982b7c4 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/last_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/last_spec.rb
@@ -1,11 +1,9 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#last" do
-    it "returns the last element of the sequence" do
-      1.step(10).last.should == 10
-      (1..10).step.last.should == 10
-      (1...10).step(4).last.should == 9
-    end
+describe "Enumerator::ArithmeticSequence#last" do
+  it "returns the last element of the sequence" do
+    1.step(10).last.should == 10
+    (1..10).step.last.should == 10
+    (1...10).step(4).last.should == 9
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/new_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/new_spec.rb
index 7227581fb9..2015983826 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/new_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/new_spec.rb
@@ -1,19 +1,17 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence.new" do
-    it "is not defined" do
-      -> {
-        Enumerator::ArithmeticSequence.new
-      }.should raise_error(NoMethodError)
-    end
+describe "Enumerator::ArithmeticSequence.new" do
+  it "is not defined" do
+    -> {
+      Enumerator::ArithmeticSequence.new
+    }.should raise_error(NoMethodError)
   end
+end
 
-  describe "Enumerator::ArithmeticSequence.allocate" do
-    it "is not defined" do
-      -> {
-        Enumerator::ArithmeticSequence.allocate
-      }.should raise_error(TypeError, 'allocator undefined for Enumerator::ArithmeticSequence')
-    end
+describe "Enumerator::ArithmeticSequence.allocate" do
+  it "is not defined" do
+    -> {
+      Enumerator::ArithmeticSequence.allocate
+    }.should raise_error(TypeError, 'allocator undefined for Enumerator::ArithmeticSequence')
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/size_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/size_spec.rb
index 00403b0238..7e03edd961 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/size_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/size_spec.rb
@@ -1,19 +1,17 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#size" do
-    context "for finite sequence" do
-      it "returns the number of elements in this arithmetic sequence" do
-        1.step(10).size.should == 10
-        (1...10).step.size.should == 9
-      end
+describe "Enumerator::ArithmeticSequence#size" do
+  context "for finite sequence" do
+    it "returns the number of elements in this arithmetic sequence" do
+      1.step(10).size.should == 10
+      (1...10).step.size.should == 9
     end
+  end
 
-    context "for infinite sequence" do
-      it "returns Infinity" do
-        1.step(Float::INFINITY).size.should == Float::INFINITY
-        (1..Float::INFINITY).step.size.should == Float::INFINITY
-      end
+  context "for infinite sequence" do
+    it "returns Infinity" do
+      1.step(Float::INFINITY).size.should == Float::INFINITY
+      (1..Float::INFINITY).step.size.should == Float::INFINITY
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/arithmetic_sequence/step_spec.rb b/spec/ruby/core/enumerator/arithmetic_sequence/step_spec.rb
index 8b00fd4309..c1f2d9173f 100644
--- a/spec/ruby/core/enumerator/arithmetic_sequence/step_spec.rb
+++ b/spec/ruby/core/enumerator/arithmetic_sequence/step_spec.rb
@@ -1,13 +1,11 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::ArithmeticSequence#step" do
-    it "returns the original value given to step method" do
-      (1..10).step.step.should == 1
-      (1..10).step(3).step.should == 3
+describe "Enumerator::ArithmeticSequence#step" do
+  it "returns the original value given to step method" do
+    (1..10).step.step.should == 1
+    (1..10).step(3).step.should == 3
 
-      1.step(10).step.should == 1
-      1.step(10, 3).step.should == 3
-    end
+    1.step(10).step.should == 1
+    1.step(10, 3).step.should == 3
   end
 end
diff --git a/spec/ruby/core/enumerator/chain/each_spec.rb b/spec/ruby/core/enumerator/chain/each_spec.rb
index ab4d355f22..cc93cbac60 100644
--- a/spec/ruby/core/enumerator/chain/each_spec.rb
+++ b/spec/ruby/core/enumerator/chain/each_spec.rb
@@ -1,17 +1,15 @@
 require_relative '../../../spec_helper'
 require_relative '../../enumerable/fixtures/classes'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::Chain#each" do
-    it "calls each on its constituents as needed" do
-      a = EnumerableSpecs::EachCounter.new(:a, :b)
-      b = EnumerableSpecs::EachCounter.new(:c, :d)
+describe "Enumerator::Chain#each" do
+  it "calls each on its constituents as needed" do
+    a = EnumerableSpecs::EachCounter.new(:a, :b)
+    b = EnumerableSpecs::EachCounter.new(:c, :d)
 
-      ScratchPad.record []
-      Enumerator::Chain.new(a, b).each do |elem|
-        ScratchPad << elem << b.times_yielded
-      end
-      ScratchPad.recorded.should == [:a, 0, :b, 0, :c, 1, :d, 2]
+    ScratchPad.record []
+    Enumerator::Chain.new(a, b).each do |elem|
+      ScratchPad << elem << b.times_yielded
     end
+    ScratchPad.recorded.should == [:a, 0, :b, 0, :c, 1, :d, 2]
   end
 end
diff --git a/spec/ruby/core/enumerator/chain/initialize_spec.rb b/spec/ruby/core/enumerator/chain/initialize_spec.rb
index e5aa32fd02..69484dfcb4 100644
--- a/spec/ruby/core/enumerator/chain/initialize_spec.rb
+++ b/spec/ruby/core/enumerator/chain/initialize_spec.rb
@@ -1,33 +1,31 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::Chain#initialize" do
-    before :each do
-      @uninitialized = Enumerator::Chain.allocate
-    end
+describe "Enumerator::Chain#initialize" do
+  before :each do
+    @uninitialized = Enumerator::Chain.allocate
+  end
 
-    it "is a private method" do
-      Enumerator::Chain.should have_private_instance_method(:initialize, false)
-    end
+  it "is a private method" do
+    Enumerator::Chain.should have_private_instance_method(:initialize, false)
+  end
 
-    it "returns self" do
-      @uninitialized.send(:initialize).should equal(@uninitialized)
-    end
+  it "returns self" do
+    @uninitialized.send(:initialize).should equal(@uninitialized)
+  end
 
-    it "accepts many arguments" do
-      @uninitialized.send(:initialize, 0..1, 2..3, 4..5).should equal(@uninitialized)
-    end
+  it "accepts many arguments" do
+    @uninitialized.send(:initialize, 0..1, 2..3, 4..5).should equal(@uninitialized)
+  end
 
-    it "accepts arguments that are not Enumerable nor responding to :each" do
-      @uninitialized.send(:initialize, Object.new).should equal(@uninitialized)
-    end
+  it "accepts arguments that are not Enumerable nor responding to :each" do
+    @uninitialized.send(:initialize, Object.new).should equal(@uninitialized)
+  end
 
-    describe "on frozen instance" do
-      it "raises a RuntimeError" do
-        -> {
-          @uninitialized.freeze.send(:initialize)
-        }.should raise_error(RuntimeError)
-      end
+  describe "on frozen instance" do
+    it "raises a RuntimeError" do
+      -> {
+        @uninitialized.freeze.send(:initialize)
+      }.should raise_error(RuntimeError)
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/chain/inspect_spec.rb b/spec/ruby/core/enumerator/chain/inspect_spec.rb
index a644d88c6f..a0450c808a 100644
--- a/spec/ruby/core/enumerator/chain/inspect_spec.rb
+++ b/spec/ruby/core/enumerator/chain/inspect_spec.rb
@@ -1,16 +1,14 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::Chain#inspect" do
-    it "shows a representation of the Enumerator" do
-      Enumerator::Chain.new.inspect.should == "#<Enumerator::Chain: []>"
-      Enumerator::Chain.new(1..2, 3..4).inspect.should == "#<Enumerator::Chain: [1..2, 3..4]>"
-    end
+describe "Enumerator::Chain#inspect" do
+  it "shows a representation of the Enumerator" do
+    Enumerator::Chain.new.inspect.should == "#<Enumerator::Chain: []>"
+    Enumerator::Chain.new(1..2, 3..4).inspect.should == "#<Enumerator::Chain: [1..2, 3..4]>"
+  end
 
-    it "calls inspect on its chain elements" do
-      obj = mock('inspect')
-      obj.should_receive(:inspect).and_return('some desc')
-      Enumerator::Chain.new(obj).inspect.should == "#<Enumerator::Chain: [some desc]>"
-    end
+  it "calls inspect on its chain elements" do
+    obj = mock('inspect')
+    obj.should_receive(:inspect).and_return('some desc')
+    Enumerator::Chain.new(obj).inspect.should == "#<Enumerator::Chain: [some desc]>"
   end
 end
diff --git a/spec/ruby/core/enumerator/chain/rewind_spec.rb b/spec/ruby/core/enumerator/chain/rewind_spec.rb
index 951b364f07..5f51ce2cf1 100644
--- a/spec/ruby/core/enumerator/chain/rewind_spec.rb
+++ b/spec/ruby/core/enumerator/chain/rewind_spec.rb
@@ -1,53 +1,51 @@
 require_relative '../../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::Chain#rewind" do
-    before(:each) do
-      @obj = mock('obj')
-      @obj.should_receive(:each).any_number_of_times.and_yield
-      @second = mock('obj')
-      @second.should_receive(:each).any_number_of_times.and_yield
-      @enum = Enumerator::Chain.new(@obj, @second)
-    end
-
-    it "returns self" do
-      @enum.rewind.should equal @enum
-    end
-
-    it "does nothing if receiver has not been iterated" do
-      @obj.should_not_receive(:rewind)
-      @obj.respond_to?(:rewind).should == true # sanity check
-      @enum.rewind
-    end
-
-    it "does nothing on objects that don't respond_to rewind" do
-      @obj.respond_to?(:rewind).should == false # sanity check
-      @enum.each {}
-      @enum.rewind
-    end
-
-    it "calls_rewind its objects" do
-      @obj.should_receive(:rewind)
-      @enum.each {}
-      @enum.rewind
-    end
-
-    it "calls_rewind in reverse order" do
-      @obj.should_not_receive(:rewind)
-      @second.should_receive(:rewind).and_raise(RuntimeError)
-      @enum.each {}
-      -> { @enum.rewind }.should raise_error(RuntimeError)
-    end
-
-    it "calls rewind only for objects that have actually been iterated on" do
-      @obj = mock('obj')
-      @obj.should_receive(:each).any_number_of_times.and_raise(RuntimeError)
-      @enum = Enumerator::Chain.new(@obj, @second)
-
-      @obj.should_receive(:rewind)
-      @second.should_not_receive(:rewind)
-      -> { @enum.each {} }.should raise_error(RuntimeError)
-      @enum.rewind
-    end
+describe "Enumerator::Chain#rewind" do
+  before(:each) do
+    @obj = mock('obj')
+    @obj.should_receive(:each).any_number_of_times.and_yield
+    @second = mock('obj')
+    @second.should_receive(:each).any_number_of_times.and_yield
+    @enum = Enumerator::Chain.new(@obj, @second)
+  end
+
+  it "returns self" do
+    @enum.rewind.should equal @enum
+  end
+
+  it "does nothing if receiver has not been iterated" do
+    @obj.should_not_receive(:rewind)
+    @obj.respond_to?(:rewind).should == true # sanity check
+    @enum.rewind
+  end
+
+  it "does nothing on objects that don't respond_to rewind" do
+    @obj.respond_to?(:rewind).should == false # sanity check
+    @enum.each {}
+    @enum.rewind
+  end
+
+  it "calls_rewind its objects" do
+    @obj.should_receive(:rewind)
+    @enum.each {}
+    @enum.rewind
+  end
+
+  it "calls_rewind in reverse order" do
+    @obj.should_not_receive(:rewind)
+    @second.should_receive(:rewind).and_raise(RuntimeError)
+    @enum.each {}
+    -> { @enum.rewind }.should raise_error(RuntimeError)
+  end
+
+  it "calls rewind only for objects that have actually been iterated on" do
+    @obj = mock('obj')
+    @obj.should_receive(:each).any_number_of_times.and_raise(RuntimeError)
+    @enum = Enumerator::Chain.new(@obj, @second)
+
+    @obj.should_receive(:rewind)
+    @second.should_not_receive(:rewind)
+    -> { @enum.each {} }.should raise_error(RuntimeError)
+    @enum.rewind
   end
 end
diff --git a/spec/ruby/core/enumerator/chain/size_spec.rb b/spec/ruby/core/enumerator/chain/size_spec.rb
index 42c31ac10b..d85b88ee8b 100644
--- a/spec/ruby/core/enumerator/chain/size_spec.rb
+++ b/spec/ruby/core/enumerator/chain/size_spec.rb
@@ -1,24 +1,22 @@
 require_relative '../../../spec_helper'
 require_relative '../../enumerable/fixtures/classes'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::Chain#size" do
-    it "returns the sum of the sizes of the elements" do
+describe "Enumerator::Chain#size" do
+  it "returns the sum of the sizes of the elements" do
+    a = mock('size')
+    a.should_receive(:size).and_return(40)
+    Enumerator::Chain.new(a, [:a, :b]).size.should == 42
+  end
+
+  it "returns nil or Infinity for the first element of such a size" do
+    [nil, Float::INFINITY].each do |special|
       a = mock('size')
       a.should_receive(:size).and_return(40)
-      Enumerator::Chain.new(a, [:a, :b]).size.should == 42
-    end
-
-    it "returns nil or Infinity for the first element of such a size" do
-      [nil, Float::INFINITY].each do |special|
-        a = mock('size')
-        a.should_receive(:size).and_return(40)
-        b = mock('special')
-        b.should_receive(:size).and_return(special)
-        c = mock('not called')
-        c.should_not_receive(:size)
-        Enumerator::Chain.new(a, b, c).size.should == special
-      end
+      b = mock('special')
+      b.should_receive(:size).and_return(special)
+      c = mock('not called')
+      c.should_not_receive(:size)
+      Enumerator::Chain.new(a, b, c).size.should == special
     end
   end
 end
diff --git a/spec/ruby/core/enumerator/lazy/filter_spec.rb b/spec/ruby/core/enumerator/lazy/filter_spec.rb
index 2ababa69cc..43128241e0 100644
--- a/spec/ruby/core/enumerator/lazy/filter_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/filter_spec.rb
@@ -1,8 +1,6 @@
 require_relative '../../../spec_helper'
 require_relative 'shared/select'
 
-ruby_version_is "2.6" do
-  describe "Enumerator::Lazy#filter" do
-    it_behaves_like :enumerator_lazy_select, :filter
-  end
+describe "Enumerator::Lazy#filter" do
+  it_behaves_like :enumerator_lazy_select, :filter
 end
diff --git a/spec/ruby/core/enumerator/lazy/with_index_spec.rb b/spec/ruby/core/enumerator/lazy/with_index_spec.rb
new file mode 100644
index 0000000000..3a59ba4116
--- /dev/null
+++ b/spec/ruby/core/enumerator/lazy/with_index_spec.rb
@@ -0,0 +1,30 @@
+# -*- encoding: us-ascii -*-
+
+require_relative '../../../spec_helper'
+require_relative 'fixtures/classes'
+
+ruby_version_is "2.7" do
+  describe "Enumerator::Lazy#with_index" do
+    it "enumerates with an index" do
+      (0..Float::INFINITY).lazy.with_index.map { |i, idx| [i, idx] }.first(3).should == [[0, 0], [1, 1], [2, 2]]
+    end
+
+    it "enumerates with an index starting at a given offset" do
+      (0..Float::INFINITY).lazy.with_index(3).map { |i, idx| [i, idx] }.first(3).should == [[0, 3], [1, 4], [2, 5]]
+    end
+
+    it "enumerates with an index starting at 0 when offset is nil" do
+      (0..Float::INFINITY).lazy.with_index(nil).map { |i, idx| [i, idx] }.first(3).should == [[0, 0], [1, 1], [2, 2]]
+    end
+
+    it "raises TypeError when offset does not convert to Integer" do
+      -> { (0..Float::INFINITY).lazy.with_index(false).map { |i, idx| i }.first(3) }.should raise_error(TypeError)
+    end
+
+    it "enumerates with a given block" do
+      result = []
+      (0..Float::INFINITY).lazy.with_index { |i, idx| result << [i * 2, idx] }.first(3)
+      result.should == [[0,0],[2,1],[4,2]]
+    end
+  end
+end
diff --git a/spec/ruby/core/enumerator/plus_spec.rb b/spec/ruby/core/enumerator/plus_spec.rb
index c9bae08b04..755be5b4eb 100644
--- a/spec/ruby/core/enumerator/plus_spec.rb
+++ b/spec/ruby/core/enumerator/plus_spec.rb
@@ -1,35 +1,33 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Enumerator#+" do
-    before :each do
-      ScratchPad.record []
-    end
+describe "Enumerator#+" do
+  before :each do
+    ScratchPad.record []
+  end
 
-    it "returns a chain of self and provided enumerators" do
-      one   = Enumerator.new { |y| y << 1 }
-      two   = Enumerator.new { |y| y << 2 }
-      three = Enumerator.new { |y| y << 3 }
+  it "returns a chain of self and provided enumerators" do
+    one   = Enumerator.new { |y| y << 1 }
+    two   = Enumerator.new { |y| y << 2 }
+    three = Enumerator.new { |y| y << 3 }
 
-      chain = one + two + three
+    chain = one + two + three
 
-      chain.should be_an_instance_of(Enumerator::Chain)
-      chain.each { |item| ScratchPad << item }
-      ScratchPad.recorded.should == [1, 2, 3]
-    end
+    chain.should be_an_instance_of(Enumerator::Chain)
+    chain.each { |item| ScratchPad << item }
+    ScratchPad.recorded.should == [1, 2, 3]
+  end
 
-    it "calls #each on each argument" do
-      enum = Enumerator.new { |y| y << "one" }
+  it "calls #each on each argument" do
+    enum = Enumerator.new { |y| y << "one" }
 
-      obj1 = mock("obj1")
-      obj1.should_receive(:each).once.and_yield("two")
+    obj1 = mock("obj1")
+    obj1.should_receive(:each).once.and_yield("two")
 
-      obj2 = mock("obj2")
-      obj2.should_receive(:each).once.and_yield("three")
+    obj2 = mock("obj2")
+    obj2.should_receive(:each).once.and_yield("three")
 
-      chain = enum + obj1 + obj2
-      chain.each { |item| ScratchPad << item }
-      ScratchPad.recorded.should == ["one", "two", "three"]
-    end
+    chain = enum + obj1 + obj2
+    chain.each { |item| ScratchPad << item }
+    ScratchPad.recorded.should == ["one", "two", "three"]
   end
 end
diff --git a/spec/ruby/core/enumerator/yielder/append_spec.rb b/spec/ruby/core/enumerator/yielder/append_spec.rb
index 7f7059774d..a36e5d64b6 100644
--- a/spec/ruby/core/enumerator/yielder/append_spec.rb
+++ b/spec/ruby/core/enumerator/yielder/append_spec.rb
@@ -23,25 +23,13 @@ describe "Enumerator::Yielder#<<" do
   end
 
   context "when multiple arguments passed" do
-    ruby_version_is '' ... '2.6' do
-      it "yields the arguments list to the block" do
-        ary = []
-        y = Enumerator::Yielder.new { |*x| ary << x }
-        y.<<(1, 2)
-
-        ary.should == [[1, 2]]
-      end
-    end
+    it "raises an ArgumentError" do
+      ary = []
+      y = Enumerator::Yielder.new { |*x| ary << x }
 
-    ruby_version_is '2.6' do
-      it "raises an ArgumentError" do
-        ary = []
-        y = Enumerator::Yielder.new { |*x| ary << x }
-
-        -> {
-          y.<<(1, 2)
-        }.should raise_error(ArgumentError, /wrong number of arguments/)
-      end
+      -> {
+        y.<<(1, 2)
+      }.should raise_error(ArgumentError, /wrong number of arguments/)
     end
   end
 end
diff --git a/spec/ruby/core/env/filter_spec.rb b/spec/ruby/core/env/filter_spec.rb
index ba18a3b33b..52f8b79a0b 100644
--- a/spec/ruby/core/env/filter_spec.rb
+++ b/spec/ruby/core/env/filter_spec.rb
@@ -2,14 +2,12 @@ require_relative '../../spec_helper'
 require_relative '../enumerable/shared/enumeratorized'
 require_relative 'shared/select'
 
-ruby_version_is "2.6" do
-  describe "ENV.filter!" do
-    it_behaves_like :env_select!, :filter!
-    it_behaves_like :enumeratorized_with_origin_size, :filter!, ENV
-  end
+describe "ENV.filter!" do
+  it_behaves_like :env_select!, :filter!
+  it_behaves_like :enumeratorized_with_origin_size, :filter!, ENV
+end
 
-  describe "ENV.filter" do
-    it_behaves_like :env_select, :filter
-    it_behaves_like :enumeratorized_with_origin_size, :filter, ENV
-  end
+describe "ENV.filter" do
+  it_behaves_like :env_select, :filter
+  it_behaves_like :enumeratorized_with_origin_size, :filter, ENV
 end
diff --git a/spec/ruby/core/env/slice_spec.rb b/spec/ruby/core/env/slice_spec.rb
index 1ac8a303f8..e3b6020391 100644
--- a/spec/ruby/core/env/slice_spec.rb
+++ b/spec/ruby/core/env/slice_spec.rb
@@ -1,29 +1,27 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "ENV.slice" do
-    before :each do
-      @saved_foo = ENV["foo"]
-      @saved_bar = ENV["bar"]
-      ENV["foo"] = "0"
-      ENV["bar"] = "1"
-    end
+describe "ENV.slice" do
+  before :each do
+    @saved_foo = ENV["foo"]
+    @saved_bar = ENV["bar"]
+    ENV["foo"] = "0"
+    ENV["bar"] = "1"
+  end
 
-    after :each do
-      ENV["foo"] = @saved_foo
-      ENV["bar"] = @saved_bar
-    end
+  after :each do
+    ENV["foo"] = @saved_foo
+    ENV["bar"] = @saved_bar
+  end
 
-    it "returns a hash of the given environment variable names and their values" do
-      ENV.slice("foo", "bar").should == {"foo" => "0", "bar" => "1"}
-    end
+  it "returns a hash of the given environment variable names and their values" do
+    ENV.slice("foo", "bar").should == {"foo" => "0", "bar" => "1"}
+  end
 
-    it "ignores each String that is not an environment variable name" do
-      ENV.slice("foo", "boo", "bar").should == {"foo" => "0", "bar" => "1"}
-    end
+  it "ignores each String that is not an environment variable name" do
+    ENV.slice("foo", "boo", "bar").should == {"foo" => "0", "bar" => "1"}
+  end
 
-    it "raises TypeError if any argument is not a String and does not respond to #to_str" do
-      -> { ENV.slice(Object.new) }.should raise_error(TypeError, "no implicit conversion of Object into String")
-    end
+  it "raises TypeError if any argument is not a String and does not respond to #to_str" do
+    -> { ENV.slice(Object.new) }.should raise_error(TypeError, "no implicit conversion of Object into String")
   end
 end
diff --git a/spec/ruby/core/env/to_h_spec.rb b/spec/ruby/core/env/to_h_spec.rb
index 65cdb59951..3c4a92aa57 100644
--- a/spec/ruby/core/env/to_h_spec.rb
+++ b/spec/ruby/core/env/to_h_spec.rb
@@ -4,57 +4,55 @@ require_relative 'shared/to_hash'
 describe "ENV.to_h" do
   it_behaves_like :env_to_hash, :to_h
 
-  ruby_version_is "2.6" do
-    context "with block" do
-      before do
-        @orig_hash = ENV.to_hash
-      end
-
-      after do
-        ENV.replace @orig_hash
-      end
-
-      it "converts [key, value] pairs returned by the block to a hash" do
-        ENV.replace("a" => "b", "c" => "d")
-        ENV.to_h { |k, v| [k, v.upcase] }.should == { 'a' => "B", 'c' => "D" }
-      end
-
-      it "does not require the array elements to be strings" do
-        ENV.replace("a" => "b", "c" => "d")
-        ENV.to_h { |k, v| [k.to_sym, v.to_sym] }.should == { :a => :b, :c => :d }
-      end
-
-      it "raises ArgumentError if block returns longer or shorter array" do
-        -> do
-          ENV.to_h { |k, v| [k, v.upcase, 1] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-
-        -> do
-          ENV.to_h { |k, v| [k] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-      end
-
-      it "raises TypeError if block returns something other than Array" do
-        -> do
-          ENV.to_h { |k, v| "not-array" }
-        end.should raise_error(TypeError, /wrong element type String/)
-      end
-
-      it "coerces returned pair to Array with #to_ary" do
-        x = mock('x')
-        x.stub!(:to_ary).and_return([:b, 'b'])
-
-        ENV.to_h { |k| x }.should == { :b => 'b' }
-      end
-
-      it "does not coerce returned pair to Array with #to_a" do
-        x = mock('x')
-        x.stub!(:to_a).and_return([:b, 'b'])
-
-        -> do
-          ENV.to_h { |k| x }
-        end.should raise_error(TypeError, /wrong element type MockObject/)
-      end
+  context "with block" do
+    before do
+      @orig_hash = ENV.to_hash
+    end
+
+    after do
+      ENV.replace @orig_hash
+    end
+
+    it "converts [key, value] pairs returned by the block to a hash" do
+      ENV.replace("a" => "b", "c" => "d")
+      ENV.to_h { |k, v| [k, v.upcase] }.should == { 'a' => "B", 'c' => "D" }
+    end
+
+    it "does not require the array elements to be strings" do
+      ENV.replace("a" => "b", "c" => "d")
+      ENV.to_h { |k, v| [k.to_sym, v.to_sym] }.should == { :a => :b, :c => :d }
+    end
+
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        ENV.to_h { |k, v| [k, v.upcase, 1] }
+      end.should raise_error(ArgumentError, /element has wrong array length/)
+
+      -> do
+        ENV.to_h { |k, v| [k] }
+      end.should raise_error(ArgumentError, /element has wrong array length/)
+    end
+
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        ENV.to_h { |k, v| "not-array" }
+      end.should raise_error(TypeError, /wrong element type String/)
+    end
+
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
+
+      ENV.to_h { |k| x }.should == { :b => 'b' }
+    end
+
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
+
+      -> do
+        ENV.to_h { |k| x }
+      end.should raise_error(TypeError, /wrong element type MockObject/)
     end
   end
 end
diff --git a/spec/ruby/core/exception/full_message_spec.rb b/spec/ruby/core/exception/full_message_spec.rb
index 9cac9fb037..4cece9ebf9 100644
--- a/spec/ruby/core/exception/full_message_spec.rb
+++ b/spec/ruby/core/exception/full_message_spec.rb
@@ -12,81 +12,77 @@ describe "Exception#full_message" do
     full_message.should include "b.rb:2"
   end
 
-  ruby_version_is "2.5.1" do
-    it "supports :highlight option and adds escape sequences to highlight some strings" do
-      e = RuntimeError.new("Some runtime error")
+  it "supports :highlight option and adds escape sequences to highlight some strings" do
+    e = RuntimeError.new("Some runtime error")
 
-      full_message = e.full_message(highlight: true, order: :bottom)
-      full_message.should include "\e[1mTraceback\e[m (most recent call last)"
-      full_message.should include "\e[1mSome runtime error (\e[1;4mRuntimeError\e[m\e[1m)"
+    full_message = e.full_message(highlight: true, order: :bottom)
+    full_message.should include "\e[1mTraceback\e[m (most recent call last)"
+    full_message.should include "\e[1mSome runtime error (\e[1;4mRuntimeError\e[m\e[1m)"
 
-      full_message = e.full_message(highlight: false, order: :bottom)
-      full_message.should include "Traceback (most recent call last)"
-      full_message.should include "Some runtime error (RuntimeError)"
-    end
+    full_message = e.full_message(highlight: false, order: :bottom)
+    full_message.should include "Traceback (most recent call last)"
+    full_message.should include "Some runtime error (RuntimeError)"
+  end
 
-    it "supports :order option and places the error message and the backtrace at the top or the bottom" do
-      e = RuntimeError.new("Some runtime error")
-      e.set_backtrace(["a.rb:1", "b.rb:2"])
+  it "supports :order option and places the error message and the backtrace at the top or the bottom" do
+    e = RuntimeError.new("Some runtime error")
+    e.set_backtrace(["a.rb:1", "b.rb:2"])
 
-      e.full_message(order: :top,    highlight: false).should =~ /a.rb:1.*b.rb:2/m
-      e.full_message(order: :bottom, highlight: false).should =~ /b.rb:2.*a.rb:1/m
-    end
+    e.full_message(order: :top,    highlight: false).should =~ /a.rb:1.*b.rb:2/m
+    e.full_message(order: :bottom, highlight: false).should =~ /b.rb:2.*a.rb:1/m
+  end
 
-    it "shows the caller if the exception has no backtrace" do
-      e = RuntimeError.new("Some runtime error")
-      e.backtrace.should == nil
-      full_message = e.full_message(highlight: false, order: :top)
-      full_message.should include("#{__FILE__}:#{__LINE__-1}:in `")
-      full_message.should include("': Some runtime error (RuntimeError)\n")
-    end
+  it "shows the caller if the exception has no backtrace" do
+    e = RuntimeError.new("Some runtime error")
+    e.backtrace.should == nil
+    full_message = e.full_message(highlight: false, order: :top)
+    full_message.should include("#{__FILE__}:#{__LINE__-1}:in `")
+    full_message.should include("': Some runtime error (RuntimeError)\n")
+  end
 
-    it "shows the exception class at the end of the first line of the message when the message contains multiple lines" do
-      begin
-        line = __LINE__; raise "first line\nsecond line"
-      rescue => e
-        full_message = e.full_message(highlight: false, order: :top).lines
-        full_message[0].should include("#{__FILE__}:#{line}:in `")
-        full_message[0].should include(": first line (RuntimeError)\n")
-        full_message[1].should == "second line\n"
-      end
+  it "shows the exception class at the end of the first line of the message when the message contains multiple lines" do
+    begin
+      line = __LINE__; raise "first line\nsecond line"
+    rescue => e
+      full_message = e.full_message(highlight: false, order: :top).lines
+      full_message[0].should include("#{__FILE__}:#{line}:in `")
+      full_message[0].should include(": first line (RuntimeError)\n")
+      full_message[1].should == "second line\n"
     end
   end
 
-  ruby_version_is "2.6" do
-    it "contains cause of exception" do
+  it "contains cause of exception" do
+    begin
       begin
-        begin
-          raise 'the cause'
-        rescue
-          raise 'main exception'
-        end
-      rescue => e
-        exception = e
+        raise 'the cause'
+      rescue
+        raise 'main exception'
       end
-
-      exception.full_message.should include "main exception"
-      exception.full_message.should include "the cause"
+    rescue => e
+      exception = e
     end
 
-    it 'contains all the chain of exceptions' do
+    exception.full_message.should include "main exception"
+    exception.full_message.should include "the cause"
+  end
+
+  it 'contains all the chain of exceptions' do
+    begin
       begin
         begin
-          begin
-            raise 'origin exception'
-          rescue
-            raise 'intermediate exception'
-          end
+          raise 'origin exception'
         rescue
-          raise 'last exception'
+          raise 'intermediate exception'
         end
-      rescue => e
-        exception = e
+      rescue
+        raise 'last exception'
       end
-
-      exception.full_message.should include "last exception"
-      exception.full_message.should include "intermediate exception"
-      exception.full_message.should include "origin exception"
+    rescue => e
+      exception = e
     end
+
+    exception.full_message.should include "last exception"
+    exception.full_message.should include "intermediate exception"
+    exception.full_message.should include "origin exception"
   end
 end
diff --git a/spec/ruby/core/exception/key_error_spec.rb b/spec/ruby/core/exception/key_error_spec.rb
index 71bf2b46ff..c5e2b1efbc 100644
--- a/spec/ruby/core/exception/key_error_spec.rb
+++ b/spec/ruby/core/exception/key_error_spec.rb
@@ -1,21 +1,19 @@
 require_relative '../../spec_helper'
 
 describe "KeyError" do
-  ruby_version_is "2.6" do
-    it "accepts :receiver and :key options" do
-      receiver = mock("receiver")
-      key = mock("key")
+  it "accepts :receiver and :key options" do
+    receiver = mock("receiver")
+    key = mock("key")
 
-      error = KeyError.new(receiver: receiver, key: key)
+    error = KeyError.new(receiver: receiver, key: key)
 
-      error.receiver.should == receiver
-      error.key.should == key
+    error.receiver.should == receiver
+    error.key.should == key
 
-      error = KeyError.new("message", receiver: receiver, key: key)
+    error = KeyError.new("message", receiver: receiver, key: key)
 
-      error.message.should == "message"
-      error.receiver.should == receiver
-      error.key.should == key
-    end
+    error.message.should == "message"
+    error.receiver.should == receiver
+    error.key.should == key
   end
 end
diff --git a/spec/ruby/core/exception/name_error_spec.rb b/spec/ruby/core/exception/name_error_spec.rb
index e901a80c42..ddd51a92e5 100644
--- a/spec/ruby/core/exception/name_error_spec.rb
+++ b/spec/ruby/core/exception/name_error_spec.rb
@@ -5,15 +5,13 @@ describe "NameError.new" do
     NameError.new("msg","name").name.should == "name"
   end
 
-  ruby_version_is "2.6" do
-    it "accepts a :receiver keyword argument" do
-      receiver = mock("receiver")
+  it "accepts a :receiver keyword argument" do
+    receiver = mock("receiver")
 
-      error = NameError.new("msg", :name, receiver: receiver)
+    error = NameError.new("msg", :name, receiver: receiver)
 
-      error.receiver.should == receiver
-      error.name.should == :name
-    end
+    error.receiver.should == receiver
+    error.name.should == :name
   end
 end
 
diff --git a/spec/ruby/core/exception/no_method_error_spec.rb b/spec/ruby/core/exception/no_method_error_spec.rb
index a93ef2187e..8428ba0382 100644
--- a/spec/ruby/core/exception/no_method_error_spec.rb
+++ b/spec/ruby/core/exception/no_method_error_spec.rb
@@ -10,15 +10,13 @@ describe "NoMethodError.new" do
     NoMethodError.new("msg").message.should == "msg"
   end
 
-  ruby_version_is "2.6" do
-    it "accepts a :receiver keyword argument" do
-      receiver = mock("receiver")
+  it "accepts a :receiver keyword argument" do
+    receiver = mock("receiver")
 
-      error = NoMethodError.new("msg", :name, receiver: receiver)
+    error = NoMethodError.new("msg", :name, receiver: receiver)
 
-      error.receiver.should == receiver
-      error.name.should == :name
-    end
+    error.receiver.should == receiver
+    error.name.should == :name
   end
 end
 
diff --git a/spec/ruby/core/exception/signal_exception_spec.rb b/spec/ruby/core/exception/signal_exception_spec.rb
index 2d2179a628..566bcb4672 100644
--- a/spec/ruby/core/exception/signal_exception_spec.rb
+++ b/spec/ruby/core/exception/signal_exception_spec.rb
@@ -30,10 +30,8 @@ describe "SignalException.new" do
     -> { SignalException.new("NONEXISTENT") }.should raise_error(ArgumentError)
   end
 
-  ruby_version_is "2.6" do
-    it "raises an exception with an invalid first argument type" do
-      -> { SignalException.new(Object.new) }.should raise_error(ArgumentError)
-    end
+  it "raises an exception with an invalid first argument type" do
+    -> { SignalException.new(Object.new) }.should raise_error(ArgumentError)
   end
 
   it "takes a signal symbol without SIG prefix as the first argument" do
diff --git a/spec/ruby/core/exception/top_level_spec.rb b/spec/ruby/core/exception/top_level_spec.rb
index 5c4514f694..b47648425e 100644
--- a/spec/ruby/core/exception/top_level_spec.rb
+++ b/spec/ruby/core/exception/top_level_spec.rb
@@ -5,29 +5,27 @@ describe "An Exception reaching the top level" do
     ruby_exe('raise "foo"', args: "2>&1", exit_status: 1).should.include?("in `<main>': foo (RuntimeError)")
   end
 
-  ruby_version_is "2.6" do
-    it "the Exception#cause is printed to STDERR with backtraces" do
-      code = <<-RUBY
-      def raise_cause
-        raise "the cause"
-      end
-      def raise_wrapped
-        raise "wrapped"
-      end
-      begin
-        raise_cause
-      rescue
-        raise_wrapped
-      end
-      RUBY
-      lines = ruby_exe(code, args: "2>&1", exit_status: 1).lines
-      lines.reject! { |l| l.include?('rescue in') }
-      lines.map! { |l| l.chomp[/:(in.+)/, 1] }
-      lines.should == ["in `raise_wrapped': wrapped (RuntimeError)",
-                       "in `<main>'",
-                       "in `raise_cause': the cause (RuntimeError)",
-                       "in `<main>'"]
+  it "the Exception#cause is printed to STDERR with backtraces" do
+    code = <<-RUBY
+    def raise_cause
+      raise "the cause"
+    end
+    def raise_wrapped
+      raise "wrapped"
+    end
+    begin
+      raise_cause
+    rescue
+      raise_wrapped
     end
+    RUBY
+    lines = ruby_exe(code, args: "2>&1", exit_status: 1).lines
+    lines.reject! { |l| l.include?('rescue in') }
+    lines.map! { |l| l.chomp[/:(in.+)/, 1] }
+    lines.should == ["in `raise_wrapped': wrapped (RuntimeError)",
+                     "in `<main>'",
+                     "in `raise_cause': the cause (RuntimeError)",
+                     "in `<main>'"]
   end
 
   describe "with a custom backtrace" do
diff --git a/spec/ruby/core/file/open_spec.rb b/spec/ruby/core/file/open_spec.rb
index 8faa31173e..c7dd34d5c6 100644
--- a/spec/ruby/core/file/open_spec.rb
+++ b/spec/ruby/core/file/open_spec.rb
@@ -629,31 +629,29 @@ describe "File.open" do
     }.should raise_error(ArgumentError, "newline decorator with binary mode")
   end
 
-  ruby_version_is "2.6" do
-    context "'x' flag" do
-      before :each do
-        @xfile = tmp("x-flag")
-        rm_r @xfile
-      end
+  context "'x' flag" do
+    before :each do
+      @xfile = tmp("x-flag")
+      rm_r @xfile
+    end
 
-      after :each do
-        rm_r @xfile
-      end
+    after :each do
+      rm_r @xfile
+    end
 
-      it "does nothing if the file doesn't exist" do
-        File.open(@xfile, "wx") { |f| f.write("content") }
-        File.read(@xfile).should == "content"
-      end
+    it "does nothing if the file doesn't exist" do
+      File.open(@xfile, "wx") { |f| f.write("content") }
+      File.read(@xfile).should == "content"
+    end
 
-      it "throws a Errno::EEXIST error if the file exists" do
-        touch @xfile
-        -> { File.open(@xfile, "wx") }.should raise_error(Errno::EEXIST)
-      end
+    it "throws a Errno::EEXIST error if the file exists" do
+      touch @xfile
+      -> { File.open(@xfile, "wx") }.should raise_error(Errno::EEXIST)
+    end
 
-      it "can't be used with 'r' and 'a' flags" do
-        -> { File.open(@xfile, "rx") }.should raise_error(ArgumentError, 'invalid access mode rx')
-        -> { File.open(@xfile, "ax") }.should raise_error(ArgumentError, 'invalid access mode ax')
-      end
+    it "can't be used with 'r' and 'a' flags" do
+      -> { File.open(@xfile, "rx") }.should raise_error(ArgumentError, 'invalid access mode rx')
+      -> { File.open(@xfile, "ax") }.should raise_error(ArgumentError, 'invalid access mode ax')
     end
   end
 end
diff --git a/spec/ruby/core/float/comparison_spec.rb b/spec/ruby/core/float/comparison_spec.rb
index cbab3a0fa1..e367198903 100644
--- a/spec/ruby/core/float/comparison_spec.rb
+++ b/spec/ruby/core/float/comparison_spec.rb
@@ -63,4 +63,28 @@ describe "Float#<=>" do
   it "returns 1 when self is negative and other is -Infinity" do
     (-Float::MAX.to_i*2 <=> -infinity_value).should == 1
   end
+
+  it "returns 0 when self is Infinity and other other is infinite?=1" do
+    obj = Object.new
+    def obj.infinite?
+      1
+    end
+    (infinity_value <=> obj).should == 0
+  end
+
+  it "returns 1 when self is Infinity and other is infinite?=-1" do
+    obj = Object.new
+    def obj.infinite?
+      -1
+    end
+    (infinity_value <=> obj).should == 1
+  end
+
+  it "returns 1 when self is Infinity and other is infinite?=nil (which means finite)" do
+    obj = Object.new
+    def obj.infinite?
+        nil
+    end
+    (infinity_value <=> obj).should == 1
+  end
 end
diff --git a/spec/ruby/core/hash/filter_spec.rb b/spec/ruby/core/hash/filter_spec.rb
index 4382c94e62..7dabe44984 100644
--- a/spec/ruby/core/hash/filter_spec.rb
+++ b/spec/ruby/core/hash/filter_spec.rb
@@ -1,12 +1,10 @@
 require_relative '../../spec_helper'
 require_relative 'shared/select'
 
-ruby_version_is "2.6" do
-  describe "Hash#filter" do
-    it_behaves_like :hash_select, :filter
-  end
+describe "Hash#filter" do
+  it_behaves_like :hash_select, :filter
+end
 
-  describe "Hash#filter!" do
-    it_behaves_like :hash_select!, :filter!
-  end
+describe "Hash#filter!" do
+  it_behaves_like :hash_select!, :filter!
 end
diff --git a/spec/ruby/core/hash/merge_spec.rb b/spec/ruby/core/hash/merge_spec.rb
index 91ded30eb7..5521864297 100644
--- a/spec/ruby/core/hash/merge_spec.rb
+++ b/spec/ruby/core/hash/merge_spec.rb
@@ -81,19 +81,17 @@ describe "Hash#merge" do
     merge_pairs.should == expected_pairs
   end
 
-  ruby_version_is "2.6" do
-    it "accepts multiple hashes" do
-      result = { a: 1 }.merge({ b: 2 }, { c: 3 }, { d: 4 })
-      result.should == { a: 1, b: 2, c: 3, d: 4 }
-    end
-
-    it "accepts zero arguments and returns a copy of self" do
-      hash = { a: 1 }
-      merged = hash.merge
-
-      merged.should eql(hash)
-      merged.should_not equal(hash)
-    end
+  it "accepts multiple hashes" do
+    result = { a: 1 }.merge({ b: 2 }, { c: 3 }, { d: 4 })
+    result.should == { a: 1, b: 2, c: 3, d: 4 }
+  end
+
+  it "accepts zero arguments and returns a copy of self" do
+    hash = { a: 1 }
+    merged = hash.merge
+
+    merged.should eql(hash)
+    merged.should_not equal(hash)
   end
 end
 
diff --git a/spec/ruby/core/hash/shared/update.rb b/spec/ruby/core/hash/shared/update.rb
index 4bb20e5b85..1b0eb809bf 100644
--- a/spec/ruby/core/hash/shared/update.rb
+++ b/spec/ruby/core/hash/shared/update.rb
@@ -64,15 +64,13 @@ describe :hash_update, shared: true do
     hash.should == {1 => :foo, 3 => :bar, 5 => 6}
   end
 
-  ruby_version_is "2.6" do
-    it "accepts multiple hashes" do
-      result = { a: 1 }.send(@method, { b: 2 }, { c: 3 }, { d: 4 })
-      result.should == { a: 1, b: 2, c: 3, d: 4 }
-    end
+  it "accepts multiple hashes" do
+    result = { a: 1 }.send(@method, { b: 2 }, { c: 3 }, { d: 4 })
+    result.should == { a: 1, b: 2, c: 3, d: 4 }
+  end
 
-    it "accepts zero arguments" do
-      hash = { a: 1 }
-      hash.send(@method).should eql(hash)
-    end
+  it "accepts zero arguments" do
+    hash = { a: 1 }
+    hash.send(@method).should eql(hash)
   end
 end
diff --git a/spec/ruby/core/hash/to_h_spec.rb b/spec/ruby/core/hash/to_h_spec.rb
index d6eaac9f33..75ebce68b1 100644
--- a/spec/ruby/core/hash/to_h_spec.rb
+++ b/spec/ruby/core/hash/to_h_spec.rb
@@ -32,43 +32,41 @@ describe "Hash#to_h" do
     end
   end
 
-  ruby_version_is "2.6" do
-    context "with block" do
-      it "converts [key, value] pairs returned by the block to a hash" do
-        { a: 1, b: 2 }.to_h { |k, v| [k.to_s, v*v]}.should == { "a" => 1, "b" => 4 }
-      end
+  context "with block" do
+    it "converts [key, value] pairs returned by the block to a hash" do
+      { a: 1, b: 2 }.to_h { |k, v| [k.to_s, v*v]}.should == { "a" => 1, "b" => 4 }
+    end
 
-      it "raises ArgumentError if block returns longer or shorter array" do
-        -> do
-          { a: 1, b: 2 }.to_h { |k, v| [k.to_s, v*v, 1] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        { a: 1, b: 2 }.to_h { |k, v| [k.to_s, v*v, 1] }
+      end.should raise_error(ArgumentError, /element has wrong array length/)
 
-        -> do
-          { a: 1, b: 2 }.to_h { |k, v| [k] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-      end
+      -> do
+        { a: 1, b: 2 }.to_h { |k, v| [k] }
+      end.should raise_error(ArgumentError, /element has wrong array length/)
+    end
 
-      it "raises TypeError if block returns something other than Array" do
-        -> do
-          { a: 1, b: 2 }.to_h { |k, v| "not-array" }
-        end.should raise_error(TypeError, /wrong element type String/)
-      end
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        { a: 1, b: 2 }.to_h { |k, v| "not-array" }
+      end.should raise_error(TypeError, /wrong element type String/)
+    end
 
-      it "coerces returned pair to Array with #to_ary" do
-        x = mock('x')
-        x.stub!(:to_ary).and_return([:b, 'b'])
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
 
-        { a: 1 }.to_h { |k| x }.should == { :b => 'b' }
-      end
+      { a: 1 }.to_h { |k| x }.should == { :b => 'b' }
+    end
 
-      it "does not coerce returned pair to Array with #to_a" do
-        x = mock('x')
-        x.stub!(:to_a).and_return([:b, 'b'])
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
 
-        -> do
-          { a: 1 }.to_h { |k| x }
-        end.should raise_error(TypeError, /wrong element type MockObject/)
-      end
+      -> do
+        { a: 1 }.to_h { |k| x }
+      end.should raise_error(TypeError, /wrong element type MockObject/)
     end
   end
 end
diff --git a/spec/ruby/core/hash/transform_keys_spec.rb b/spec/ruby/core/hash/transform_keys_spec.rb
index 4f4544a6c5..70a4cdde36 100644
--- a/spec/ruby/core/hash/transform_keys_spec.rb
+++ b/spec/ruby/core/hash/transform_keys_spec.rb
@@ -60,31 +60,12 @@ describe "Hash#transform_keys!" do
   end
 
   # https://bugs.ruby-lang.org/issues/14380
-  ruby_version_is ""..."2.5.1" do
-    it "does not prevent conflicts between new keys and old ones" do
-      @hash.transform_keys!(&:succ)
-      @hash.should == { e: 1 }
-    end
-  end
-
-  ruby_version_is "2.5.1" do
-    it "prevents conflicts between new keys and old ones" do
-      @hash.transform_keys!(&:succ)
-      @hash.should == { b: 1, c: 2, d: 3, e: 4 }
-    end
-  end
-
-  ruby_version_is ""..."2.5.1" do
-    it "partially modifies the contents if we broke from the block" do
-      @hash.transform_keys! do |v|
-        break if v == :c
-        v.succ
-      end
-      @hash.should == { c: 1, d: 4 }
-    end
+  it "prevents conflicts between new keys and old ones" do
+    @hash.transform_keys!(&:succ)
+    @hash.should == { b: 1, c: 2, d: 3, e: 4 }
   end
 
-  ruby_version_is "2.5.1"..."3.0.2" do # https://bugs.ruby-lang.org/issues/17735
+  ruby_version_is ""..."3.0.2" do # https://bugs.ruby-lang.org/issues/17735
     it "returns the processed keys if we broke from the block" do
       @hash.transform_keys! do |v|
         break if v == :c
diff --git a/spec/ruby/core/io/set_encoding_by_bom_spec.rb b/spec/ruby/core/io/set_encoding_by_bom_spec.rb
index c551042bee..7368ec7677 100644
--- a/spec/ruby/core/io/set_encoding_by_bom_spec.rb
+++ b/spec/ruby/core/io/set_encoding_by_bom_spec.rb
@@ -67,5 +67,11 @@ describe "IO#set_encoding_by_bom" do
 
       -> { @io.set_encoding_by_bom }.should raise_error(ArgumentError, 'encoding is set to UTF-8 already')
     end
+
+    it 'returns exception if encoding conversion is already set' do
+      @io.set_encoding(Encoding::UTF_8, Encoding::UTF_16BE)
+
+      -> { @io.set_encoding_by_bom }.should raise_error(ArgumentError, 'encoding conversion is set')
+    end
   end
 end
diff --git a/spec/ruby/core/io/ungetbyte_spec.rb b/spec/ruby/core/io/ungetbyte_spec.rb
index 1e2ec77e1f..776707205a 100644
--- a/spec/ruby/core/io/ungetbyte_spec.rb
+++ b/spec/ruby/core/io/ungetbyte_spec.rb
@@ -36,20 +36,7 @@ describe "IO#ungetbyte" do
     @io.getbyte.should == 97
   end
 
-  ruby_version_is ''...'2.6' do
-    it "puts back one byte for an Integer argument..." do
-      @io.ungetbyte(4095).should be_nil
-      @io.getbyte.should == 255
-    end
-
-    it "... but not for Integer argument (eh?)" do
-      -> {
-        @io.ungetbyte(0x4f7574206f6620636861722072616e6765)
-      }.should raise_error(TypeError)
-    end
-  end
-
-  ruby_version_is '2.6'...'2.6.1' do
+  ruby_version_is ''...'2.6.1' do
     it "is an RangeError if the integer is not in 8bit" do
       for i in [4095, 0x4f7574206f6620636861722072616e6765] do
         -> { @io.ungetbyte(i) }.should raise_error(RangeError)
diff --git a/spec/ruby/core/kernel/Complex_spec.rb b/spec/ruby/core/kernel/Complex_spec.rb
index 37f9843931..4f043526b8 100644
--- a/spec/ruby/core/kernel/Complex_spec.rb
+++ b/spec/ruby/core/kernel/Complex_spec.rb
@@ -139,48 +139,46 @@ describe "Kernel.Complex()" do
     end
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed exception: false" do
-      describe "and [Numeric]" do
-        it "returns a complex number" do
-          Complex("123", exception: false).should == Complex(123)
-        end
+  describe "when passed exception: false" do
+    describe "and [Numeric]" do
+      it "returns a complex number" do
+        Complex("123", exception: false).should == Complex(123)
       end
+    end
 
-      describe "and [non-Numeric]" do
-        it "swallows an error" do
-          Complex(:sym, exception: false).should == nil
-        end
+    describe "and [non-Numeric]" do
+      it "swallows an error" do
+        Complex(:sym, exception: false).should == nil
       end
+    end
 
-      describe "and [non-Numeric, Numeric] argument" do
-        it "throws a TypeError" do
-          -> { Complex(:sym, 0, exception: false) }.should raise_error(TypeError, "not a real")
-        end
+    describe "and [non-Numeric, Numeric] argument" do
+      it "throws a TypeError" do
+        -> { Complex(:sym, 0, exception: false) }.should raise_error(TypeError, "not a real")
       end
+    end
 
-      describe "and [anything, non-Numeric] argument" do
-        it "swallows an error" do
-          Complex("a",  :sym, exception: false).should == nil
-          Complex(:sym, :sym, exception: false).should == nil
-          Complex(0,    :sym, exception: false).should == nil
-        end
+    describe "and [anything, non-Numeric] argument" do
+      it "swallows an error" do
+        Complex("a",  :sym, exception: false).should == nil
+        Complex(:sym, :sym, exception: false).should == nil
+        Complex(0,    :sym, exception: false).should == nil
       end
+    end
 
-      describe "and non-numeric String arguments" do
-        it "swallows an error" do
-          Complex("a", "b", exception: false).should == nil
-          Complex("a", 0, exception: false).should == nil
-          Complex(0, "b", exception: false).should == nil
-        end
+    describe "and non-numeric String arguments" do
+      it "swallows an error" do
+        Complex("a", "b", exception: false).should == nil
+        Complex("a", 0, exception: false).should == nil
+        Complex(0, "b", exception: false).should == nil
       end
+    end
 
-      describe "and nil arguments" do
-        it "swallows an error" do
-          Complex(nil, exception: false).should == nil
-          Complex(0, nil, exception: false).should == nil
-          Complex(nil, 0, exception: false).should == nil
-        end
+    describe "and nil arguments" do
+      it "swallows an error" do
+        Complex(nil, exception: false).should == nil
+        Complex(0, nil, exception: false).should == nil
+        Complex(nil, 0, exception: false).should == nil
       end
     end
   end
diff --git a/spec/ruby/core/kernel/Float_spec.rb b/spec/ruby/core/kernel/Float_spec.rb
index af64fcbe86..015bcb33d6 100644
--- a/spec/ruby/core/kernel/Float_spec.rb
+++ b/spec/ruby/core/kernel/Float_spec.rb
@@ -306,27 +306,25 @@ describe :kernel_float, shared: true do
     -> { @object.send(:Float, c) }.should raise_error(RangeError)
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed exception: false" do
-      describe "and valid input" do
-        it "returns a Float number" do
-          @object.send(:Float, 1, exception: false).should == 1.0
-          @object.send(:Float, "1", exception: false).should == 1.0
-          @object.send(:Float, "1.23", exception: false).should == 1.23
-        end
+  describe "when passed exception: false" do
+    describe "and valid input" do
+      it "returns a Float number" do
+        @object.send(:Float, 1, exception: false).should == 1.0
+        @object.send(:Float, "1", exception: false).should == 1.0
+        @object.send(:Float, "1.23", exception: false).should == 1.23
       end
+    end
 
-      describe "and invalid input" do
-        it "swallows an error" do
-          @object.send(:Float, "abc", exception: false).should == nil
-          @object.send(:Float, :sym, exception: false).should == nil
-        end
+    describe "and invalid input" do
+      it "swallows an error" do
+        @object.send(:Float, "abc", exception: false).should == nil
+        @object.send(:Float, :sym, exception: false).should == nil
       end
+    end
 
-      describe "and nil" do
-        it "swallows it" do
-          @object.send(:Float, nil, exception: false).should == nil
-        end
+    describe "and nil" do
+      it "swallows it" do
+        @object.send(:Float, nil, exception: false).should == nil
       end
     end
   end
diff --git a/spec/ruby/core/kernel/Integer_spec.rb b/spec/ruby/core/kernel/Integer_spec.rb
index 74bea7ca09..2c78e27428 100644
--- a/spec/ruby/core/kernel/Integer_spec.rb
+++ b/spec/ruby/core/kernel/Integer_spec.rb
@@ -10,29 +10,18 @@ describe :kernel_integer, shared: true do
     Integer(100).should == 100
   end
 
-  ruby_version_is ""..."2.6" do
-    it "uncritically return the value of to_int even if it is not an Integer" do
-      obj = mock("object")
-      obj.should_receive(:to_int).and_return("1")
-      obj.should_not_receive(:to_i)
-      Integer(obj).should == "1"
-    end
+  it "raises a TypeError when to_int returns not-an-Integer object and to_i returns nil" do
+    obj = mock("object")
+    obj.should_receive(:to_int).and_return("1")
+    obj.should_receive(:to_i).and_return(nil)
+    -> { Integer(obj) }.should raise_error(TypeError)
   end
 
-  ruby_version_is "2.6" do
-    it "raises a TypeError when to_int returns not-an-Integer object and to_i returns nil" do
-      obj = mock("object")
-      obj.should_receive(:to_int).and_return("1")
-      obj.should_receive(:to_i).and_return(nil)
-      -> { Integer(obj) }.should raise_error(TypeError)
-    end
-
-    it "return a result of to_i when to_int does not return an Integer" do
-      obj = mock("object")
-      obj.should_receive(:to_int).and_return("1")
-      obj.should_receive(:to_i).and_return(42)
-      Integer(obj).should == 42
-    end
+  it "return a result of to_i when to_int does not return an Integer" do
+    obj = mock("object")
+    obj.should_receive(:to_int).and_return("1")
+    obj.should_receive(:to_i).and_return(42)
+    Integer(obj).should == 42
   end
 
   it "raises a TypeError when passed nil" do
@@ -100,59 +89,57 @@ describe :kernel_integer, shared: true do
     -> { Integer(infinity_value) }.should raise_error(FloatDomainError)
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed exception: false" do
-      describe "and to_i returns a value that is not an Integer" do
-        it "swallows an error" do
-          obj = mock("object")
-          obj.should_receive(:to_i).and_return("1")
-          Integer(obj, exception: false).should == nil
-        end
+  describe "when passed exception: false" do
+    describe "and to_i returns a value that is not an Integer" do
+      it "swallows an error" do
+        obj = mock("object")
+        obj.should_receive(:to_i).and_return("1")
+        Integer(obj, exception: false).should == nil
       end
+    end
 
-      describe "and no to_int or to_i methods exist" do
-        it "swallows an error" do
-          obj = mock("object")
-          Integer(obj, exception: false).should == nil
-        end
+    describe "and no to_int or to_i methods exist" do
+      it "swallows an error" do
+        obj = mock("object")
+        Integer(obj, exception: false).should == nil
       end
+    end
 
-      describe "and to_int returns nil and no to_i exists" do
-        it "swallows an error" do
-          obj = mock("object")
-          obj.should_receive(:to_i).and_return(nil)
-          Integer(obj, exception: false).should == nil
-        end
+    describe "and to_int returns nil and no to_i exists" do
+      it "swallows an error" do
+        obj = mock("object")
+        obj.should_receive(:to_i).and_return(nil)
+        Integer(obj, exception: false).should == nil
       end
+    end
 
-      describe "and passed NaN" do
-        it "swallows an error" do
-          Integer(nan_value, exception: false).should == nil
-        end
+    describe "and passed NaN" do
+      it "swallows an error" do
+        Integer(nan_value, exception: false).should == nil
       end
+    end
 
-      describe "and passed Infinity" do
-        it "swallows an error" do
-          Integer(infinity_value, exception: false).should == nil
-        end
+    describe "and passed Infinity" do
+      it "swallows an error" do
+        Integer(infinity_value, exception: false).should == nil
       end
+    end
 
-      describe "and passed nil" do
-        it "swallows an error" do
-          Integer(nil, exception: false).should == nil
-        end
+    describe "and passed nil" do
+      it "swallows an error" do
+        Integer(nil, exception: false).should == nil
       end
+    end
 
-      describe "and passed a String that contains numbers" do
-        it "normally parses it and returns an Integer" do
-          Integer("42", exception: false).should == 42
-        end
+    describe "and passed a String that contains numbers" do
+      it "normally parses it and returns an Integer" do
+        Integer("42", exception: false).should == 42
       end
+    end
 
-      describe "and passed a String that can't be converted to an Integer" do
-        it "swallows an error" do
-          Integer("abc", exception: false).should == nil
-        end
+    describe "and passed a String that can't be converted to an Integer" do
+      it "swallows an error" do
+        Integer("abc", exception: false).should == nil
       end
     end
   end
@@ -246,30 +233,28 @@ describe "Integer() given a String", shared: true do
     -> { Integer("") }.should raise_error(ArgumentError)
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed exception: false" do
-      describe "and multiple leading -s" do
-        it "swallows an error" do
-          Integer("---1", exception: false).should == nil
-        end
+  describe "when passed exception: false" do
+    describe "and multiple leading -s" do
+      it "swallows an error" do
+        Integer("---1", exception: false).should == nil
       end
+    end
 
-      describe "and multiple trailing -s" do
-        it "swallows an error" do
-          Integer("1---", exception: false).should == nil
-        end
+    describe "and multiple trailing -s" do
+      it "swallows an error" do
+        Integer("1---", exception: false).should == nil
       end
+    end
 
-      describe "and an argument that contains a period" do
-        it "swallows an error" do
-          Integer("0.0", exception: false).should == nil
-        end
+    describe "and an argument that contains a period" do
+      it "swallows an error" do
+        Integer("0.0", exception: false).should == nil
       end
+    end
 
-      describe "and an empty string" do
-        it "swallows an error" do
-          Integer("", exception: false).should == nil
-        end
+    describe "and an empty string" do
+      it "swallows an error" do
+        Integer("", exception: false).should == nil
       end
     end
   end
@@ -594,20 +579,18 @@ describe "Integer() given a String and base", shared: true do
     end
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed exception: false" do
-      describe "and valid argument" do
-        it "returns an Integer number" do
-          Integer("100", 10, exception: false).should == 100
-          Integer("100", 2, exception: false).should == 4
-        end
+  describe "when passed exception: false" do
+    describe "and valid argument" do
+      it "returns an Integer number" do
+        Integer("100", 10, exception: false).should == 100
+        Integer("100", 2, exception: false).should == 4
       end
+    end
 
-      describe "and invalid argument" do
-        it "swallows an error" do
-          Integer("999", 2, exception: false).should == nil
-          Integer("abc", 10, exception: false).should == nil
-        end
+    describe "and invalid argument" do
+      it "swallows an error" do
+        Integer("999", 2, exception: false).should == nil
+        Integer("abc", 10, exception: false).should == nil
       end
     end
   end
diff --git a/spec/ruby/core/kernel/autoload_spec.rb b/spec/ruby/core/kernel/autoload_spec.rb
index 8d56021fa8..0404caec6d 100644
--- a/spec/ruby/core/kernel/autoload_spec.rb
+++ b/spec/ruby/core/kernel/autoload_spec.rb
@@ -56,6 +56,21 @@ describe "Kernel#autoload" do
     end
   end
 
+  describe "inside a Class.new method body" do
+    # NOTE: this spec is being discussed in https://github.com/ruby/spec/pull/839
+    it "should define on the new anonymous class" do
+      cls = Class.new do
+        def go
+          autoload :Object, 'bogus'
+          autoload? :Object
+        end
+      end
+
+      cls.new.go.should == 'bogus'
+      cls.autoload?(:Object).should == 'bogus'
+    end
+  end
+
   describe "when Object is frozen" do
     it "raises a FrozenError before defining the constant" do
       ruby_exe(fixture(__FILE__, "autoload_frozen.rb")).should == "FrozenError - nil"
diff --git a/spec/ruby/core/kernel/caller_locations_spec.rb b/spec/ruby/core/kernel/caller_locations_spec.rb
index bbb7e7b737..3ec8f0f432 100644
--- a/spec/ruby/core/kernel/caller_locations_spec.rb
+++ b/spec/ruby/core/kernel/caller_locations_spec.rb
@@ -28,12 +28,10 @@ describe 'Kernel#caller_locations' do
     locations1[2..4].map(&:to_s).should == locations2.map(&:to_s)
   end
 
-  ruby_version_is "2.6" do
-    it "works with endless ranges" do
-      locations1 = caller_locations(0)
-      locations2 = caller_locations(eval("(2..)"))
-      locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
-    end
+  it "works with endless ranges" do
+    locations1 = caller_locations(0)
+    locations2 = caller_locations(eval("(2..)"))
+    locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/kernel/caller_spec.rb b/spec/ruby/core/kernel/caller_spec.rb
index 6c175868cb..dba65ddcb0 100644
--- a/spec/ruby/core/kernel/caller_spec.rb
+++ b/spec/ruby/core/kernel/caller_spec.rb
@@ -44,12 +44,10 @@ describe 'Kernel#caller' do
     ]
   end
 
-  ruby_version_is "2.6" do
-    it "works with endless ranges" do
-      locations1 = KernelSpecs::CallerTest.locations(0)
-      locations2 = KernelSpecs::CallerTest.locations(eval("(2..)"))
-      locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
-    end
+  it "works with endless ranges" do
+    locations1 = KernelSpecs::CallerTest.locations(0)
+    locations2 = KernelSpecs::CallerTest.locations(eval("(2..)"))
+    locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/kernel/match_spec.rb b/spec/ruby/core/kernel/match_spec.rb
index 6dc1eb7de8..fbfc77f959 100644
--- a/spec/ruby/core/kernel/match_spec.rb
+++ b/spec/ruby/core/kernel/match_spec.rb
@@ -14,11 +14,9 @@ describe "Kernel#=~" do
     end
   end
 
-  ruby_version_is "2.6" do
-    it "is deprecated" do
-      -> do
-        Object.new =~ /regexp/
-      end.should complain(/deprecated Object#=~ is called on Object/, verbose: true)
-    end
+  it "is deprecated" do
+    -> do
+      Object.new =~ /regexp/
+    end.should complain(/deprecated Object#=~ is called on Object/, verbose: true)
   end
 end
diff --git a/spec/ruby/core/kernel/open_spec.rb b/spec/ruby/core/kernel/open_spec.rb
index 981b5291b3..8d936d8ca0 100644
--- a/spec/ruby/core/kernel/open_spec.rb
+++ b/spec/ruby/core/kernel/open_spec.rb
@@ -2,7 +2,6 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 describe "Kernel#open" do
-
   before :each do
     @name = tmp("kernel_open.txt")
     @content = "This is a test"
@@ -137,6 +136,18 @@ describe "Kernel#open" do
   it "accepts nil for mode and permission" do
     open(@name, nil, nil) { |f| f.gets }.should == @content
   end
+
+  ruby_version_is ""..."3.0" do
+    it "works correctly when redefined by open-uri" do
+      code = <<~RUBY
+      require 'open-uri'
+      obj = Object.new
+      def obj.to_open; self; end
+      p open(obj) == obj
+      RUBY
+      ruby_exe(code, args: "2>&1").should == "true\n"
+    end
+  end
 end
 
 describe "Kernel.open" do
diff --git a/spec/ruby/core/kernel/raise_spec.rb b/spec/ruby/core/kernel/raise_spec.rb
index 6dac132498..4f190c120b 100644
--- a/spec/ruby/core/kernel/raise_spec.rb
+++ b/spec/ruby/core/kernel/raise_spec.rb
@@ -28,25 +28,23 @@ describe "Kernel#raise" do
     ScratchPad.recorded.should be_nil
   end
 
-  ruby_version_is "2.6" do
-    it "accepts a cause keyword argument that sets the cause" do
+  it "accepts a cause keyword argument that sets the cause" do
+    cause = StandardError.new
+    -> { raise("error", cause: cause) }.should raise_error(RuntimeError) { |e| e.cause.should == cause }
+  end
+
+  it "accepts a cause keyword argument that overrides the last exception" do
+    begin
+      raise "first raise"
+    rescue => ignored
       cause = StandardError.new
       -> { raise("error", cause: cause) }.should raise_error(RuntimeError) { |e| e.cause.should == cause }
     end
+  end
 
-    it "accepts a cause keyword argument that overrides the last exception" do
-      begin
-        raise "first raise"
-      rescue => ignored
-        cause = StandardError.new
-        -> { raise("error", cause: cause) }.should raise_error(RuntimeError) { |e| e.cause.should == cause }
-      end
-    end
-
-    it "raises an ArgumentError when only cause is given" do
-      cause = StandardError.new
-      -> { raise(cause: cause) }.should raise_error(ArgumentError)
-    end
+  it "raises an ArgumentError when only cause is given" do
+    cause = StandardError.new
+    -> { raise(cause: cause) }.should raise_error(ArgumentError)
   end
 end
 
diff --git a/spec/ruby/core/kernel/system_spec.rb b/spec/ruby/core/kernel/system_spec.rb
index 696e6ae3d7..9671a650cc 100644
--- a/spec/ruby/core/kernel/system_spec.rb
+++ b/spec/ruby/core/kernel/system_spec.rb
@@ -25,14 +25,12 @@ describe :kernel_system, shared: true do
     $?.exitstatus.should == 1
   end
 
-  ruby_version_is "2.6" do
-    it "raises RuntimeError when `exception: true` is given and the command exits with a non-zero exit status" do
-      -> { @object.system(ruby_cmd('exit 1'), exception: true) }.should raise_error(RuntimeError)
-    end
+  it "raises RuntimeError when `exception: true` is given and the command exits with a non-zero exit status" do
+    -> { @object.system(ruby_cmd('exit 1'), exception: true) }.should raise_error(RuntimeError)
+  end
 
-    it "raises Errno::ENOENT when `exception: true` is given and the specified command does not exist" do
-      -> { @object.system('feature_14386', exception: true) }.should raise_error(Errno::ENOENT)
-    end
+  it "raises Errno::ENOENT when `exception: true` is given and the specified command does not exist" do
+    -> { @object.system('feature_14386', exception: true) }.should raise_error(Errno::ENOENT)
   end
 
   it "returns nil when command execution fails" do
diff --git a/spec/ruby/core/kernel/then_spec.rb b/spec/ruby/core/kernel/then_spec.rb
index fa896b52b1..8109a2960a 100644
--- a/spec/ruby/core/kernel/then_spec.rb
+++ b/spec/ruby/core/kernel/then_spec.rb
@@ -1,8 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'shared/then'
 
-ruby_version_is "2.6" do
-  describe "Kernel#then" do
-    it_behaves_like :kernel_then, :then
-  end
+describe "Kernel#then" do
+  it_behaves_like :kernel_then, :then
 end
diff --git a/spec/ruby/core/kernel/warn_spec.rb b/spec/ruby/core/kernel/warn_spec.rb
index 5953a47e81..511e741f32 100644
--- a/spec/ruby/core/kernel/warn_spec.rb
+++ b/spec/ruby/core/kernel/warn_spec.rb
@@ -107,11 +107,9 @@ describe "Kernel#warn" do
       ruby_exe(file, options: "--disable-gems", args: "2>&1").should == "#{file}:2: warning: warn-require-warning\n"
     end
 
-    ruby_version_is "2.6" do
-      it "shows the caller of #require and not #require itself with RubyGems loaded" do
-        file = fixture(__FILE__ , "warn_require_caller.rb")
-        ruby_exe(file, options: "-rrubygems", args: "2>&1").should == "#{file}:2: warning: warn-require-warning\n"
-      end
+    it "shows the caller of #require and not #require itself with RubyGems loaded" do
+      file = fixture(__FILE__ , "warn_require_caller.rb")
+      ruby_exe(file, options: "-rrubygems", args: "2>&1").should == "#{file}:2: warning: warn-require-warning\n"
     end
 
     guard -> { Kernel.instance_method(:tap).source_location } do
diff --git a/spec/ruby/core/marshal/dump_spec.rb b/spec/ruby/core/marshal/dump_spec.rb
index 8d6ba245af..a54a4c6735 100644
--- a/spec/ruby/core/marshal/dump_spec.rb
+++ b/spec/ruby/core/marshal/dump_spec.rb
@@ -78,6 +78,20 @@ describe "Marshal.dump" do
       s = "\u2192".force_encoding("binary").to_sym
       Marshal.dump(s).should == "\x04\b:\b\xE2\x86\x92"
     end
+
+    it "dumps multiple Symbols sharing the same encoding" do
+      # Note that the encoding is a link for the second Symbol
+      symbol1 = "I:\t\xE2\x82\xACa\x06:\x06ET"
+      symbol2 = "I:\t\xE2\x82\xACb\x06;\x06T"
+      value = [
+        "€a".force_encoding(Encoding::UTF_8).to_sym,
+        "€b".force_encoding(Encoding::UTF_8).to_sym
+      ]
+      Marshal.dump(value).should == "\x04\b[\a#{symbol1}#{symbol2}"
+
+      value = [*value, value[0]]
+      Marshal.dump(value).should == "\x04\b[\b#{symbol1}#{symbol2};\x00"
+    end
   end
 
   describe "with an object responding to #marshal_dump" do
@@ -343,8 +357,13 @@ describe "Marshal.dump" do
     end
 
     it "dumps an extended Struct" do
-      st = Struct.new("Extended", :a, :b).new
-      Marshal.dump(st.extend(Meths)).should == "\004\be:\nMethsS:\025Struct::Extended\a:\006a0:\006b0"
+      obj = Struct.new("Extended", :a, :b).new.extend(Meths)
+      Marshal.dump(obj).should == "\004\be:\nMethsS:\025Struct::Extended\a:\006a0:\006b0"
+
+      s = 'hi'
+      obj.a = [:a, s]
+      obj.b = [:Meths, s]
+      Marshal.dump(obj).should == "\004\be:\nMethsS:\025Struct::Extended\a:\006a[\a;\a\"\ahi:\006b[\a;\000@\a"
       Struct.send(:remove_const, :Extended)
     end
   end
diff --git a/spec/ruby/core/marshal/fixtures/marshal_data.rb b/spec/ruby/core/marshal/fixtures/marshal_data.rb
index bf58f4888d..9373ef7ba8 100644
--- a/spec/ruby/core/marshal/fixtures/marshal_data.rb
+++ b/spec/ruby/core/marshal/fixtures/marshal_data.rb
@@ -83,7 +83,7 @@ class UserPreviouslyDefinedWithInitializedIvar
 end
 
 class UserMarshal
-  attr_reader :data
+  attr_accessor :data
 
   def initialize
     @data = 'stuff'
diff --git a/spec/ruby/core/marshal/shared/load.rb b/spec/ruby/core/marshal/shared/load.rb
index 4e940c80a8..a79fb51cd7 100644
--- a/spec/ruby/core/marshal/shared/load.rb
+++ b/spec/ruby/core/marshal/shared/load.rb
@@ -309,7 +309,8 @@ describe :marshal_load, shared: true do
 
     it "loads an extended Array object containing a user-marshaled object" do
       obj = [UserMarshal.new, UserMarshal.new].extend(Meths)
-      new_obj = Marshal.send(@method, "\x04\be:\nMeths[\ao:\x10UserMarshal\x06:\n@dataI\"\nstuff\x06:\x06ETo;\x06\x06;\aI\"\nstuff\x06;\bT")
+      dump = "\x04\be:\nMeths[\ao:\x10UserMarshal\x06:\n@dataI\"\nstuff\x06:\x06ETo;\x06\x06;\aI\"\nstuff\x06;\bT"
+      new_obj = Marshal.send(@method, dump)
 
       new_obj.should == obj
       obj_ancestors = class << obj; ancestors[1..-1]; end
@@ -399,6 +400,24 @@ describe :marshal_load, shared: true do
       sym.should == s
       sym.encoding.should == Encoding::BINARY
     end
+
+    it "loads multiple Symbols sharing the same encoding" do
+      # Note that the encoding is a link for the second Symbol
+      symbol1 = "I:\t\xE2\x82\xACa\x06:\x06ET"
+      symbol2 = "I:\t\xE2\x82\xACb\x06;\x06T"
+      dump = "\x04\b[\a#{symbol1}#{symbol2}"
+      value = Marshal.send(@method, dump)
+      value.map(&:encoding).should == [Encoding::UTF_8, Encoding::UTF_8]
+      expected = [
+        "€a".force_encoding(Encoding::UTF_8).to_sym,
+        "€b".force_encoding(Encoding::UTF_8).to_sym
+      ]
+      value.should == expected
+
+      value = Marshal.send(@method, "\x04\b[\b#{symbol1}#{symbol2};\x00")
+      value.map(&:encoding).should == [Encoding::UTF_8, Encoding::UTF_8, Encoding::UTF_8]
+      value.should == [*expected, expected[0]]
+    end
   end
 
   describe "for a String" do
@@ -460,20 +479,23 @@ describe :marshal_load, shared: true do
   describe "for a Struct" do
     it "loads a extended_struct having fields with same objects" do
       s = 'hi'
-      obj = Struct.new("Ure2", :a, :b).new.extend(Meths)
+      obj = Struct.new("Extended", :a, :b).new.extend(Meths)
+      dump = "\004\be:\nMethsS:\025Struct::Extended\a:\006a0:\006b0"
+      Marshal.send(@method, dump).should == obj
+
       obj.a = [:a, s]
       obj.b = [:Meths, s]
-
-      Marshal.send(@method,
-        "\004\be:\nMethsS:\021Struct::Ure2\a:\006a[\a;\a\"\ahi:\006b[\a;\000@\a"
-        ).should == obj
-      Struct.send(:remove_const, :Ure2)
+      dump = "\004\be:\nMethsS:\025Struct::Extended\a:\006a[\a;\a\"\ahi:\006b[\a;\000@\a"
+      Marshal.send(@method, dump).should == obj
+      Struct.send(:remove_const, :Extended)
     end
 
     it "loads a struct having ivar" do
       obj = Struct.new("Thick").new
       obj.instance_variable_set(:@foo, 5)
-      Marshal.send(@method, "\004\bIS:\022Struct::Thick\000\006:\t@fooi\n").should == obj
+      reloaded = Marshal.send(@method, "\004\bIS:\022Struct::Thick\000\006:\t@fooi\n")
+      reloaded.should == obj
+      reloaded.instance_variable_get(:@foo).should == 5
       Struct.send(:remove_const, :Thick)
     end
 
@@ -588,6 +610,18 @@ describe :marshal_load, shared: true do
     end
   end
 
+  describe "for an object responding to #marshal_dump and #marshal_load" do
+    it "loads a user-marshaled object" do
+      obj = UserMarshal.new
+      obj.data = :data
+      value = [obj, :data]
+      dump = Marshal.dump(value)
+      dump.should == "\x04\b[\aU:\x10UserMarshal:\tdata;\x06"
+      reloaded = Marshal.load(dump)
+      reloaded.should == value
+    end
+  end
+
   describe "for a user object" do
     it "loads a user-marshaled extended object" do
       obj = UserMarshal.new.extend(Meths)
diff --git a/spec/ruby/core/method/compose_spec.rb b/spec/ruby/core/method/compose_spec.rb
index 0743dd4f8d..87cf61f7ad 100644
--- a/spec/ruby/core/method/compose_spec.rb
+++ b/spec/ruby/core/method/compose_spec.rb
@@ -2,101 +2,99 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative '../proc/shared/compose'
 
-ruby_version_is "2.6" do
-  describe "Method#<<" do
-    it "returns a Proc that is the composition of self and the passed Proc" do
-      succ = MethodSpecs::Composition.new.method(:succ)
-      upcase = proc { |s| s.upcase }
+describe "Method#<<" do
+  it "returns a Proc that is the composition of self and the passed Proc" do
+    succ = MethodSpecs::Composition.new.method(:succ)
+    upcase = proc { |s| s.upcase }
 
-      (succ << upcase).call('Ruby').should == "RUBZ"
-    end
+    (succ << upcase).call('Ruby').should == "RUBZ"
+  end
 
-    it "calls passed Proc with arguments and then calls self with result" do
-      pow_2_proc = proc { |x| x * x }
-      double_proc = proc { |x| x + x }
+  it "calls passed Proc with arguments and then calls self with result" do
+    pow_2_proc = proc { |x| x * x }
+    double_proc = proc { |x| x + x }
 
-      pow_2_method = MethodSpecs::Composition.new.method(:pow_2)
-      double_method = MethodSpecs::Composition.new.method(:double)
+    pow_2_method = MethodSpecs::Composition.new.method(:pow_2)
+    double_method = MethodSpecs::Composition.new.method(:double)
 
-      (pow_2_method << double_proc).call(2).should == 16
-      (double_method << pow_2_proc).call(2).should == 8
-    end
+    (pow_2_method << double_proc).call(2).should == 16
+    (double_method << pow_2_proc).call(2).should == 8
+  end
 
-    it "accepts any callable object" do
-      inc = MethodSpecs::Composition.new.method(:inc)
+  it "accepts any callable object" do
+    inc = MethodSpecs::Composition.new.method(:inc)
 
-      double = Object.new
-      def double.call(n); n * 2; end
+    double = Object.new
+    def double.call(n); n * 2; end
 
-      (inc << double).call(3).should == 7
-    end
+    (inc << double).call(3).should == 7
+  end
 
-    it_behaves_like :proc_compose, :<<, -> { MethodSpecs::Composition.new.method(:upcase) }
+  it_behaves_like :proc_compose, :<<, -> { MethodSpecs::Composition.new.method(:upcase) }
 
-    describe "composition" do
-      it "is a lambda" do
-        pow_2 = MethodSpecs::Composition.new.method(:pow_2)
-        double = proc { |x| x + x }
+  describe "composition" do
+    it "is a lambda" do
+      pow_2 = MethodSpecs::Composition.new.method(:pow_2)
+      double = proc { |x| x + x }
 
-        (pow_2 << double).is_a?(Proc).should == true
-        ruby_version_is(''...'3.0') { (pow_2 << double).should.lambda? }
-        ruby_version_is('3.0') { (pow_2 << double).should_not.lambda? }
-      end
+      (pow_2 << double).is_a?(Proc).should == true
+      ruby_version_is(''...'3.0') { (pow_2 << double).should.lambda? }
+      ruby_version_is('3.0') { (pow_2 << double).should_not.lambda? }
+    end
 
-      it "may accept multiple arguments" do
-        inc = MethodSpecs::Composition.new.method(:inc)
-        mul = proc { |n, m| n * m }
+    it "may accept multiple arguments" do
+      inc = MethodSpecs::Composition.new.method(:inc)
+      mul = proc { |n, m| n * m }
 
-        (inc << mul).call(2, 3).should == 7
-      end
+      (inc << mul).call(2, 3).should == 7
     end
   end
+end
 
-  describe "Method#>>" do
-    it "returns a Proc that is the composition of self and the passed Proc" do
-      upcase = proc { |s| s.upcase }
-      succ = MethodSpecs::Composition.new.method(:succ)
+describe "Method#>>" do
+  it "returns a Proc that is the composition of self and the passed Proc" do
+    upcase = proc { |s| s.upcase }
+    succ = MethodSpecs::Composition.new.method(:succ)
 
-      (succ >> upcase).call('Ruby').should == "RUBZ"
-    end
+    (succ >> upcase).call('Ruby').should == "RUBZ"
+  end
 
-    it "calls passed Proc with arguments and then calls self with result" do
-      pow_2_proc = proc { |x| x * x }
-      double_proc = proc { |x| x + x }
+  it "calls passed Proc with arguments and then calls self with result" do
+    pow_2_proc = proc { |x| x * x }
+    double_proc = proc { |x| x + x }
 
-      pow_2_method = MethodSpecs::Composition.new.method(:pow_2)
-      double_method = MethodSpecs::Composition.new.method(:double)
+    pow_2_method = MethodSpecs::Composition.new.method(:pow_2)
+    double_method = MethodSpecs::Composition.new.method(:double)
 
-      (pow_2_method >> double_proc).call(2).should == 8
-      (double_method >> pow_2_proc).call(2).should == 16
-    end
+    (pow_2_method >> double_proc).call(2).should == 8
+    (double_method >> pow_2_proc).call(2).should == 16
+  end
 
-    it "accepts any callable object" do
-      inc = MethodSpecs::Composition.new.method(:inc)
+  it "accepts any callable object" do
+    inc = MethodSpecs::Composition.new.method(:inc)
 
-      double = Object.new
-      def double.call(n); n * 2; end
+    double = Object.new
+    def double.call(n); n * 2; end
 
-      (inc >> double).call(3).should == 8
-    end
+    (inc >> double).call(3).should == 8
+  end
 
-    it_behaves_like :proc_compose, :>>, -> { MethodSpecs::Composition.new.method(:upcase) }
+  it_behaves_like :proc_compose, :>>, -> { MethodSpecs::Composition.new.method(:upcase) }
 
-    describe "composition" do
-      it "is a lambda" do
-        pow_2 = MethodSpecs::Composition.new.method(:pow_2)
-        double = proc { |x| x + x }
+  describe "composition" do
+    it "is a lambda" do
+      pow_2 = MethodSpecs::Composition.new.method(:pow_2)
+      double = proc { |x| x + x }
 
-        (pow_2 >> double).is_a?(Proc).should == true
-        (pow_2 >> double).should.lambda?
-      end
+      (pow_2 >> double).is_a?(Proc).should == true
+      (pow_2 >> double).should.lambda?
+    end
 
-      it "may accept multiple arguments" do
-        mul = MethodSpecs::Composition.new.method(:mul)
-        inc = proc { |n| n + 1 }
+    it "may accept multiple arguments" do
+      mul = MethodSpecs::Composition.new.method(:mul)
+      inc = proc { |n| n + 1 }
 
-        (mul >> inc).call(2, 3).should == 7
-      end
+      (mul >> inc).call(2, 3).should == 7
     end
   end
 end
diff --git a/spec/ruby/core/module/include_spec.rb b/spec/ruby/core/module/include_spec.rb
index c7ead1079c..128b9af2bf 100644
--- a/spec/ruby/core/module/include_spec.rb
+++ b/spec/ruby/core/module/include_spec.rb
@@ -376,6 +376,162 @@ describe "Module#include" do
 
     foo.call.should == 'n'
   end
+
+  it "updates the constant when an included module is updated" do
+    module ModuleSpecs::ConstUpdated
+      module A
+        FOO = 'a'
+      end
+
+      module M
+      end
+
+      module B
+        include A
+        include M
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+
+      M.const_set(:FOO, 'm')
+      B.foo.should == 'm'
+    end
+  end
+
+  it "updates the constant when a module included after a call is later updated" do
+    module ModuleSpecs::ConstLaterUpdated
+      module A
+        FOO = 'a'
+      end
+
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+
+      module M
+      end
+      B.include M
+
+      B.foo.should == 'a'
+
+      M.const_set(:FOO, 'm')
+      B.foo.should == 'm'
+    end
+  end
+
+  it "updates the constant when a module included in another module after a call is later updated" do
+    module ModuleSpecs::ConstModuleLaterUpdated
+      module A
+        FOO = 'a'
+      end
+
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+
+      module M
+      end
+      B.include M
+
+      B.foo.should == 'a'
+
+      M.const_set(:FOO, 'm')
+      B.foo.should == 'm'
+    end
+  end
+
+  it "updates the constant when a nested included module is updated" do
+    module ModuleSpecs::ConstUpdatedNestedIncludeUpdated
+      module A
+        FOO = 'a'
+      end
+
+      module N
+      end
+
+      module M
+        include N
+      end
+
+      module B
+        include A
+        include M
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+
+      N.const_set(:FOO, 'n')
+      B.foo.should == 'n'
+    end
+  end
+
+  it "updates the constant when a new module is included" do
+    module ModuleSpecs::ConstUpdatedNewInclude
+      module A
+        FOO = 'a'
+      end
+
+      module M
+        FOO = 'm'
+      end
+
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+
+      B.include(M)
+      B.foo.should == 'm'
+    end
+  end
+
+  it "updates the constant when a new module with nested module is included" do
+    module ModuleSpecs::ConstUpdatedNestedIncluded
+      module A
+        FOO = 'a'
+      end
+
+      module N
+        FOO = 'n'
+      end
+
+      module M
+        include N
+      end
+
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+
+      B.include M
+      B.foo.should == 'n'
+    end
+  end
 end
 
 describe "Module#include?" do
diff --git a/spec/ruby/core/module/method_defined_spec.rb b/spec/ruby/core/module/method_defined_spec.rb
index dccee870b1..bc5b420e11 100644
--- a/spec/ruby/core/module/method_defined_spec.rb
+++ b/spec/ruby/core/module/method_defined_spec.rb
@@ -47,54 +47,52 @@ describe "Module#method_defined?" do
     c.method_defined?(o).should == true
   end
 
-  ruby_version_is "2.6" do
-    # works as method_defined?(method_name)
-    describe "when passed true as a second optional argument" do
-      it "performs a lookup in ancestors" do
-        ModuleSpecs::Child.method_defined?(:public_child, true).should == true
-        ModuleSpecs::Child.method_defined?(:protected_child, true).should == true
-        ModuleSpecs::Child.method_defined?(:accessor_method, true).should == true
-        ModuleSpecs::Child.method_defined?(:private_child, true).should == false
-
-        # Defined in Parent
-        ModuleSpecs::Child.method_defined?(:public_parent, true).should == true
-        ModuleSpecs::Child.method_defined?(:protected_parent, true).should == true
-        ModuleSpecs::Child.method_defined?(:private_parent, true).should == false
-
-        # Defined in Module
-        ModuleSpecs::Child.method_defined?(:public_module, true).should == true
-        ModuleSpecs::Child.method_defined?(:protected_module, true).should == true
-        ModuleSpecs::Child.method_defined?(:private_module, true).should == false
-
-        # Defined in SuperModule
-        ModuleSpecs::Child.method_defined?(:public_super_module, true).should == true
-        ModuleSpecs::Child.method_defined?(:protected_super_module, true).should == true
-        ModuleSpecs::Child.method_defined?(:private_super_module, true).should == false
-      end
+  # works as method_defined?(method_name)
+  describe "when passed true as a second optional argument" do
+    it "performs a lookup in ancestors" do
+      ModuleSpecs::Child.method_defined?(:public_child, true).should == true
+      ModuleSpecs::Child.method_defined?(:protected_child, true).should == true
+      ModuleSpecs::Child.method_defined?(:accessor_method, true).should == true
+      ModuleSpecs::Child.method_defined?(:private_child, true).should == false
+
+      # Defined in Parent
+      ModuleSpecs::Child.method_defined?(:public_parent, true).should == true
+      ModuleSpecs::Child.method_defined?(:protected_parent, true).should == true
+      ModuleSpecs::Child.method_defined?(:private_parent, true).should == false
+
+      # Defined in Module
+      ModuleSpecs::Child.method_defined?(:public_module, true).should == true
+      ModuleSpecs::Child.method_defined?(:protected_module, true).should == true
+      ModuleSpecs::Child.method_defined?(:private_module, true).should == false
+
+      # Defined in SuperModule
+      ModuleSpecs::Child.method_defined?(:public_super_module, true).should == true
+      ModuleSpecs::Child.method_defined?(:protected_super_module, true).should == true
+      ModuleSpecs::Child.method_defined?(:private_super_module, true).should == false
     end
+  end
 
-    describe "when passed false as a second optional argument" do
-      it "checks only the class itself" do
-        ModuleSpecs::Child.method_defined?(:public_child, false).should == true
-        ModuleSpecs::Child.method_defined?(:protected_child, false).should == true
-        ModuleSpecs::Child.method_defined?(:accessor_method, false).should == true
-        ModuleSpecs::Child.method_defined?(:private_child, false).should == false
-
-        # Defined in Parent
-        ModuleSpecs::Child.method_defined?(:public_parent, false).should == false
-        ModuleSpecs::Child.method_defined?(:protected_parent, false).should == false
-        ModuleSpecs::Child.method_defined?(:private_parent, false).should == false
-
-        # Defined in Module
-        ModuleSpecs::Child.method_defined?(:public_module, false).should == false
-        ModuleSpecs::Child.method_defined?(:protected_module, false).should == false
-        ModuleSpecs::Child.method_defined?(:private_module, false).should == false
-
-        # Defined in SuperModule
-        ModuleSpecs::Child.method_defined?(:public_super_module, false).should == false
-        ModuleSpecs::Child.method_defined?(:protected_super_module, false).should == false
-        ModuleSpecs::Child.method_defined?(:private_super_module, false).should == false
-      end
+  describe "when passed false as a second optional argument" do
+    it "checks only the class itself" do
+      ModuleSpecs::Child.method_defined?(:public_child, false).should == true
+      ModuleSpecs::Child.method_defined?(:protected_child, false).should == true
+      ModuleSpecs::Child.method_defined?(:accessor_method, false).should == true
+      ModuleSpecs::Child.method_defined?(:private_child, false).should == false
+
+      # Defined in Parent
+      ModuleSpecs::Child.method_defined?(:public_parent, false).should == false
+      ModuleSpecs::Child.method_defined?(:protected_parent, false).should == false
+      ModuleSpecs::Child.method_defined?(:private_parent, false).should == false
+
+      # Defined in Module
+      ModuleSpecs::Child.method_defined?(:public_module, false).should == false
+      ModuleSpecs::Child.method_defined?(:protected_module, false).should == false
+      ModuleSpecs::Child.method_defined?(:private_module, false).should == false
+
+      # Defined in SuperModule
+      ModuleSpecs::Child.method_defined?(:public_super_module, false).should == false
+      ModuleSpecs::Child.method_defined?(:protected_super_module, false).should == false
+      ModuleSpecs::Child.method_defined?(:private_super_module, false).should == false
     end
   end
 end
diff --git a/spec/ruby/core/module/prepend_spec.rb b/spec/ruby/core/module/prepend_spec.rb
index f11ca1b8b6..04cc27d472 100644
--- a/spec/ruby/core/module/prepend_spec.rb
+++ b/spec/ruby/core/module/prepend_spec.rb
@@ -222,6 +222,191 @@ describe "Module#prepend" do
     foo.call.should == 'n'
   end
 
+  it "updates the constant when a module is prepended" do
+    module ModuleSpecs::ConstUpdatePrepended
+      module M
+        FOO = 'm'
+      end
+      module A
+        FOO = 'a'
+      end
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+
+      B.foo.should == 'a'
+      B.prepend M
+      B.foo.should == 'm'
+    end
+  end
+
+  it "updates the constant when a prepended module is updated" do
+    module ModuleSpecs::ConstPrependedUpdated
+      module M
+      end
+      module A
+        FOO = 'a'
+      end
+      module B
+        include A
+        prepend M
+        def self.foo
+          FOO
+        end
+      end
+      B.foo.should == 'a'
+      M.const_set(:FOO, 'm')
+      B.foo.should == 'm'
+    end
+  end
+
+  it "updates the constant when there is a base included constant and the prepended module overrides it" do
+    module ModuleSpecs::ConstIncludedPrependedOverride
+      module Base
+        FOO = 'a'
+      end
+      module A
+        include Base
+        def self.foo
+          FOO
+        end
+      end
+      A.foo.should == 'a'
+
+      module M
+        FOO = 'm'
+      end
+      A.prepend M
+      A.foo.should == 'm'
+    end
+  end
+
+  it "updates the constant when there is a base included constant and the prepended module is later updated" do
+    module ModuleSpecs::ConstIncludedPrependedLaterUpdated
+      module Base
+        FOO = 'a'
+      end
+      module A
+        include Base
+        def self.foo
+          FOO
+        end
+      end
+      A.foo.should == 'a'
+
+      module M
+      end
+      A.prepend M
+      A.foo.should == 'a'
+
+      M.const_set(:FOO, 'm')
+      A.foo.should == 'm'
+    end
+  end
+
+  it "updates the constant when a module prepended after a constant is later updated" do
+    module ModuleSpecs::ConstUpdatedPrependedAfterLaterUpdated
+      module M
+      end
+      module A
+        FOO = 'a'
+      end
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+      B.foo.should == 'a'
+
+      B.prepend M
+      B.foo.should == 'a'
+
+      M.const_set(:FOO, 'm')
+      B.foo.should == 'm'
+    end
+  end
+
+  it "updates the constant when a module is prepended after another and the constant is defined later on that module" do
+    module ModuleSpecs::ConstUpdatedPrependedAfterConstDefined
+      module M
+        FOO = 'm'
+      end
+      module A
+        prepend M
+        def self.foo
+          FOO
+        end
+      end
+
+      A.foo.should == 'm'
+
+      module N
+      end
+      A.prepend N
+      A.foo.should == 'm'
+
+      N.const_set(:FOO, 'n')
+      A.foo.should == 'n'
+    end
+  end
+
+  it "updates the constant when a module is included in a prepended module and the constant is defined later" do
+    module ModuleSpecs::ConstUpdatedIncludedInPrependedConstDefinedLater
+      module A
+        def self.foo
+          FOO
+        end
+      end
+      module Base
+        FOO = 'a'
+      end
+
+      A.prepend Base
+      A.foo.should == 'a'
+
+      module N
+      end
+      module M
+        include N
+      end
+
+      A.prepend M
+
+      N.const_set(:FOO, 'n')
+      A.foo.should == 'n'
+    end
+  end
+
+  it "updates the constant when a new module with an included module is prepended" do
+    module ModuleSpecs::ConstUpdatedNewModuleIncludedPrepended
+      module A
+        FOO = 'a'
+      end
+      module B
+        include A
+        def self.foo
+          FOO
+        end
+      end
+      module N
+        FOO = 'n'
+      end
+
+      module M
+        include N
+      end
+
+      B.foo.should == 'a'
+
+      B.prepend M
+      B.foo.should == 'n'
+    end
+  end
+
   it "raises a TypeError when the argument is not a Module" do
     -> { ModuleSpecs::Basic.prepend(Class.new) }.should raise_error(TypeError)
   end
diff --git a/spec/ruby/core/module/private_method_defined_spec.rb b/spec/ruby/core/module/private_method_defined_spec.rb
index 951f17aaa7..01fc8f8fb9 100644
--- a/spec/ruby/core/module/private_method_defined_spec.rb
+++ b/spec/ruby/core/module/private_method_defined_spec.rb
@@ -70,53 +70,51 @@ describe "Module#private_method_defined?" do
     ModuleSpecs::CountsMixin.private_method_defined?(str).should == true
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed true as a second optional argument" do
-      it "performs a lookup in ancestors" do
-        ModuleSpecs::Child.private_method_defined?(:public_child, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_child, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:accessor_method, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_child, true).should == true
-
-        # Defined in Parent
-        ModuleSpecs::Child.private_method_defined?(:public_parent, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_parent, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_parent, true).should == true
-
-        # Defined in Module
-        ModuleSpecs::Child.private_method_defined?(:public_module, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_module, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_module, true).should == true
-
-        # Defined in SuperModule
-        ModuleSpecs::Child.private_method_defined?(:public_super_module, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_super_module, true).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_super_module, true).should == true
-      end
+  describe "when passed true as a second optional argument" do
+    it "performs a lookup in ancestors" do
+      ModuleSpecs::Child.private_method_defined?(:public_child, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_child, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:accessor_method, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_child, true).should == true
+
+      # Defined in Parent
+      ModuleSpecs::Child.private_method_defined?(:public_parent, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_parent, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_parent, true).should == true
+
+      # Defined in Module
+      ModuleSpecs::Child.private_method_defined?(:public_module, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_module, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_module, true).should == true
+
+      # Defined in SuperModule
+      ModuleSpecs::Child.private_method_defined?(:public_super_module, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_super_module, true).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_super_module, true).should == true
     end
+  end
 
-    describe "when passed false as a second optional argument" do
-      it "checks only the class itself" do
-        ModuleSpecs::Child.private_method_defined?(:public_child, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_child, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:accessor_method, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_child, false).should == true
-
-        # Defined in Parent
-        ModuleSpecs::Child.private_method_defined?(:public_parent, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_parent, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_parent, false).should == false
-
-        # Defined in Module
-        ModuleSpecs::Child.private_method_defined?(:public_module, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_module, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_module, false).should == false
-
-        # Defined in SuperModule
-        ModuleSpecs::Child.private_method_defined?(:public_super_module, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:protected_super_module, false).should == false
-        ModuleSpecs::Child.private_method_defined?(:private_super_module, false).should == false
-      end
+  describe "when passed false as a second optional argument" do
+    it "checks only the class itself" do
+      ModuleSpecs::Child.private_method_defined?(:public_child, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_child, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:accessor_method, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_child, false).should == true
+
+      # Defined in Parent
+      ModuleSpecs::Child.private_method_defined?(:public_parent, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_parent, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_parent, false).should == false
+
+      # Defined in Module
+      ModuleSpecs::Child.private_method_defined?(:public_module, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_module, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_module, false).should == false
+
+      # Defined in SuperModule
+      ModuleSpecs::Child.private_method_defined?(:public_super_module, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:protected_super_module, false).should == false
+      ModuleSpecs::Child.private_method_defined?(:private_super_module, false).should == false
     end
   end
 end
diff --git a/spec/ruby/core/module/protected_method_defined_spec.rb b/spec/ruby/core/module/protected_method_defined_spec.rb
index e022d7c5c4..31e24a16c1 100644
--- a/spec/ruby/core/module/protected_method_defined_spec.rb
+++ b/spec/ruby/core/module/protected_method_defined_spec.rb
@@ -70,53 +70,51 @@ describe "Module#protected_method_defined?" do
     ModuleSpecs::CountsMixin.protected_method_defined?(str).should == true
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed true as a second optional argument" do
-      it "performs a lookup in ancestors" do
-        ModuleSpecs::Child.protected_method_defined?(:public_child, true).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_child, true).should == true
-        ModuleSpecs::Child.protected_method_defined?(:accessor_method, true).should == false
-        ModuleSpecs::Child.protected_method_defined?(:private_child, true).should == false
-
-        # Defined in Parent
-        ModuleSpecs::Child.protected_method_defined?(:public_parent, true).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_parent, true).should == true
-        ModuleSpecs::Child.protected_method_defined?(:private_parent, true).should == false
-
-        # Defined in Module
-        ModuleSpecs::Child.protected_method_defined?(:public_module, true).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_module, true).should == true
-        ModuleSpecs::Child.protected_method_defined?(:private_module, true).should == false
-
-        # Defined in SuperModule
-        ModuleSpecs::Child.protected_method_defined?(:public_super_module, true).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_super_module, true).should == true
-        ModuleSpecs::Child.protected_method_defined?(:private_super_module, true).should == false
-      end
+  describe "when passed true as a second optional argument" do
+    it "performs a lookup in ancestors" do
+      ModuleSpecs::Child.protected_method_defined?(:public_child, true).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_child, true).should == true
+      ModuleSpecs::Child.protected_method_defined?(:accessor_method, true).should == false
+      ModuleSpecs::Child.protected_method_defined?(:private_child, true).should == false
+
+      # Defined in Parent
+      ModuleSpecs::Child.protected_method_defined?(:public_parent, true).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_parent, true).should == true
+      ModuleSpecs::Child.protected_method_defined?(:private_parent, true).should == false
+
+      # Defined in Module
+      ModuleSpecs::Child.protected_method_defined?(:public_module, true).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_module, true).should == true
+      ModuleSpecs::Child.protected_method_defined?(:private_module, true).should == false
+
+      # Defined in SuperModule
+      ModuleSpecs::Child.protected_method_defined?(:public_super_module, true).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_super_module, true).should == true
+      ModuleSpecs::Child.protected_method_defined?(:private_super_module, true).should == false
     end
+  end
 
-    describe "when passed false as a second optional argument" do
-      it "checks only the class itself" do
-        ModuleSpecs::Child.protected_method_defined?(:public_child, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_child, false).should == true
-        ModuleSpecs::Child.protected_method_defined?(:accessor_method, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:private_child, false).should == false
-
-        # Defined in Parent
-        ModuleSpecs::Child.protected_method_defined?(:public_parent, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_parent, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:private_parent, false).should == false
-
-        # Defined in Module
-        ModuleSpecs::Child.protected_method_defined?(:public_module, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_module, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:private_module, false).should == false
-
-        # Defined in SuperModule
-        ModuleSpecs::Child.protected_method_defined?(:public_super_module, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:protected_super_module, false).should == false
-        ModuleSpecs::Child.protected_method_defined?(:private_super_module, false).should == false
-      end
+  describe "when passed false as a second optional argument" do
+    it "checks only the class itself" do
+      ModuleSpecs::Child.protected_method_defined?(:public_child, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_child, false).should == true
+      ModuleSpecs::Child.protected_method_defined?(:accessor_method, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:private_child, false).should == false
+
+      # Defined in Parent
+      ModuleSpecs::Child.protected_method_defined?(:public_parent, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_parent, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:private_parent, false).should == false
+
+      # Defined in Module
+      ModuleSpecs::Child.protected_method_defined?(:public_module, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_module, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:private_module, false).should == false
+
+      # Defined in SuperModule
+      ModuleSpecs::Child.protected_method_defined?(:public_super_module, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:protected_super_module, false).should == false
+      ModuleSpecs::Child.protected_method_defined?(:private_super_module, false).should == false
     end
   end
 end
diff --git a/spec/ruby/core/module/refine_spec.rb b/spec/ruby/core/module/refine_spec.rb
index e5f65f5f96..e3b7fde049 100644
--- a/spec/ruby/core/module/refine_spec.rb
+++ b/spec/ruby/core/module/refine_spec.rb
@@ -453,44 +453,22 @@ describe "Module#refine" do
       result.should == ["(1)", "(2)", "(3)"]
     end
 
-    ruby_version_is "" ... "2.6" do
-      it "is not honored by Kernel#public_send" do
-        refined_class = ModuleSpecs.build_refined_class
-
-        refinement = Module.new do
-          refine refined_class do
-            def foo; "foo from refinement"; end
-          end
-        end
+    it "is honored by Kernel#public_send" do
+      refined_class = ModuleSpecs.build_refined_class
 
-        result = nil
-        Module.new do
-          using refinement
-          result = refined_class.new.public_send :foo
+      refinement = Module.new do
+        refine refined_class do
+          def foo; "foo from refinement"; end
         end
-
-        result.should == "foo"
       end
-    end
-
-    ruby_version_is "2.6" do
-      it "is honored by Kernel#public_send" do
-        refined_class = ModuleSpecs.build_refined_class
-
-        refinement = Module.new do
-          refine refined_class do
-            def foo; "foo from refinement"; end
-          end
-        end
 
-        result = nil
-        Module.new do
-          using refinement
-          result = refined_class.new.public_send :foo
-        end
-
-        result.should == "foo from refinement"
+      result = nil
+      Module.new do
+        using refinement
+        result = refined_class.new.public_send :foo
       end
+
+      result.should == "foo from refinement"
     end
 
     it "is honored by string interpolation" do
@@ -647,81 +625,39 @@ describe "Module#refine" do
       end
     end
 
-    ruby_version_is "" ... "2.6" do
-      it "is not honored by Kernel#respond_to?" do
-        klass = Class.new
-        refinement = Module.new do
-          refine klass do
-            def foo; end
-          end
-        end
-
-        result = nil
-        Module.new do
-          using refinement
-          result = klass.new.respond_to?(:foo)
+    it "is honored by Kernel#respond_to?" do
+      klass = Class.new
+      refinement = Module.new do
+        refine klass do
+          def foo; end
         end
-
-        result.should == false
       end
-    end
-
-    ruby_version_is "2.6" do
-      it "is honored by Kernel#respond_to?" do
-        klass = Class.new
-        refinement = Module.new do
-          refine klass do
-            def foo; end
-          end
-        end
-
-        result = nil
-        Module.new do
-          using refinement
-          result = klass.new.respond_to?(:foo)
-        end
 
-        result.should == true
+      result = nil
+      Module.new do
+        using refinement
+        result = klass.new.respond_to?(:foo)
       end
-    end
 
-    ruby_version_is ""..."2.6" do
-      it "is not honored by &" do
-        refinement = Module.new do
-          refine String do
-            def to_proc(*args)
-              -> * { 'foo' }
-            end
-          end
-        end
-
-        -> do
-          Module.new do
-            using refinement
-            ["hola"].map(&"upcase")
-          end
-        end.should raise_error(TypeError, /wrong argument type String \(expected Proc\)/)
-      end
+      result.should == true
     end
 
-    ruby_version_is "2.6" do
-      it "is honored by &" do
-        refinement = Module.new do
-          refine String do
-            def to_proc(*args)
-              -> * { 'foo' }
-            end
+    it "is honored by &" do
+      refinement = Module.new do
+        refine String do
+          def to_proc(*args)
+            -> * { 'foo' }
           end
         end
+      end
 
-        result = nil
-        Module.new do
-          using refinement
-          result = ["hola"].map(&"upcase")
-        end
-
-        result.should == ['foo']
+      result = nil
+      Module.new do
+        using refinement
+        result = ["hola"].map(&"upcase")
       end
+
+      result.should == ['foo']
     end
   end
 
diff --git a/spec/ruby/core/module/remove_const_spec.rb b/spec/ruby/core/module/remove_const_spec.rb
index 20eb2dc3ed..0ac23f05a5 100644
--- a/spec/ruby/core/module/remove_const_spec.rb
+++ b/spec/ruby/core/module/remove_const_spec.rb
@@ -81,4 +81,25 @@ describe "Module#remove_const" do
     ConstantSpecs.autoload :AutoloadedConstant, 'a_file'
     ConstantSpecs.send(:remove_const, :AutoloadedConstant).should be_nil
   end
+
+  it "updates the constant value" do
+    module ConstantSpecs::RemovedConstantUpdate
+      module M
+        FOO = 'm'
+      end
+
+      module A
+        include M
+        FOO = 'a'
+        def self.foo
+          FOO
+        end
+      end
+
+      A.foo.should == 'a'
+
+      A.send(:remove_const,:FOO)
+      A.foo.should == 'm'
+    end
+  end
 end
diff --git a/spec/ruby/core/nil/match_spec.rb b/spec/ruby/core/nil/match_spec.rb
index 27646e9749..2e2b5d1c1b 100644
--- a/spec/ruby/core/nil/match_spec.rb
+++ b/spec/ruby/core/nil/match_spec.rb
@@ -1,23 +1,21 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "NilClass#=~" do
-    it "returns nil matching any object" do
-      o = Object.new
+describe "NilClass#=~" do
+  it "returns nil matching any object" do
+    o = Object.new
 
-      suppress_warning do
-        (o =~ /Object/).should   be_nil
-        (o =~ 'Object').should   be_nil
-        (o =~ Object).should     be_nil
-        (o =~ Object.new).should be_nil
-        (o =~ nil).should        be_nil
-        (o =~ false).should      be_nil
-        (o =~ true).should       be_nil
-      end
+    suppress_warning do
+      (o =~ /Object/).should   be_nil
+      (o =~ 'Object').should   be_nil
+      (o =~ Object).should     be_nil
+      (o =~ Object.new).should be_nil
+      (o =~ nil).should        be_nil
+      (o =~ false).should      be_nil
+      (o =~ true).should       be_nil
     end
+  end
 
-    it "should not warn" do
-      -> { nil =~ /a/ }.should_not complain(verbose: true)
-    end
+  it "should not warn" do
+    -> { nil =~ /a/ }.should_not complain(verbose: true)
   end
 end
diff --git a/spec/ruby/core/numeric/shared/step.rb b/spec/ruby/core/numeric/shared/step.rb
index 72f33016d4..a4fe74f9db 100644
--- a/spec/ruby/core/numeric/shared/step.rb
+++ b/spec/ruby/core/numeric/shared/step.rb
@@ -257,9 +257,7 @@ describe :numeric_step, :shared => true do
 
   describe "when no block is given" do
     step_enum_class = Enumerator
-    ruby_version_is "2.6" do
-      step_enum_class = Enumerator::ArithmeticSequence
-    end
+    step_enum_class = Enumerator::ArithmeticSequence
 
     ruby_version_is ""..."3.0" do
       it "returns an #{step_enum_class} when step is 0" do
diff --git a/spec/ruby/core/numeric/step_spec.rb b/spec/ruby/core/numeric/step_spec.rb
index 2773000229..03af8b0e4d 100644
--- a/spec/ruby/core/numeric/step_spec.rb
+++ b/spec/ruby/core/numeric/step_spec.rb
@@ -22,9 +22,7 @@ describe "Numeric#step" do
 
     describe "when no block is given" do
       step_enum_class = Enumerator
-      ruby_version_is "2.6" do
-        step_enum_class = Enumerator::ArithmeticSequence
-      end
+      step_enum_class = Enumerator::ArithmeticSequence
 
       ruby_version_is ""..."3.0" do
         it "returns an #{step_enum_class} when step is 0" do
@@ -38,19 +36,7 @@ describe "Numeric#step" do
 
       describe "returned #{step_enum_class}" do
         describe "size" do
-          ruby_version_is ""..."2.6" do
-            it "raises an ArgumentError when step is 0" do
-              enum = 1.step(5, 0)
-              -> { enum.size }.should raise_error(ArgumentError)
-            end
-
-            it "raises an ArgumentError when step is 0.0" do
-              enum = 1.step(2, 0.0)
-              -> { enum.size }.should raise_error(ArgumentError)
-            end
-          end
-
-          ruby_version_is "2.6"..."3.0" do
+          ruby_version_is ""..."3.0" do
             it "is infinity when step is 0" do
               enum = 1.step(5, 0)
               enum.size.should == Float::INFINITY
@@ -69,16 +55,8 @@ describe "Numeric#step" do
         end
 
         describe "type" do
-          ruby_version_is ""..."2.6" do
-            it "returns an instance of Enumerator" do
-              1.step(10).class.should == Enumerator
-            end
-          end
-
-          ruby_version_is "2.6" do
-            it "returns an instance of Enumerator::ArithmeticSequence" do
-              1.step(10).class.should == Enumerator::ArithmeticSequence
-            end
+          it "returns an instance of Enumerator::ArithmeticSequence" do
+            1.step(10).class.should == Enumerator::ArithmeticSequence
           end
         end
       end
diff --git a/spec/ruby/core/proc/compose_spec.rb b/spec/ruby/core/proc/compose_spec.rb
index 285e96192b..803a32af7b 100644
--- a/spec/ruby/core/proc/compose_spec.rb
+++ b/spec/ruby/core/proc/compose_spec.rb
@@ -1,156 +1,154 @@
 require_relative '../../spec_helper'
 require_relative 'shared/compose'
 
-ruby_version_is "2.6" do
-  describe "Proc#<<" do
-    it "returns a Proc that is the composition of self and the passed Proc" do
-      upcase = proc { |s| s.upcase }
-      succ = proc { |s| s.succ }
+describe "Proc#<<" do
+  it "returns a Proc that is the composition of self and the passed Proc" do
+    upcase = proc { |s| s.upcase }
+    succ = proc { |s| s.succ }
 
-      (succ << upcase).call('Ruby').should == "RUBZ"
-    end
+    (succ << upcase).call('Ruby').should == "RUBZ"
+  end
 
-    it "calls passed Proc with arguments and then calls self with result" do
-      f = proc { |x| x * x }
-      g = proc { |x| x + x }
+  it "calls passed Proc with arguments and then calls self with result" do
+    f = proc { |x| x * x }
+    g = proc { |x| x + x }
 
-      (f << g).call(2).should == 16
-      (g << f).call(2).should == 8
-    end
+    (f << g).call(2).should == 16
+    (g << f).call(2).should == 8
+  end
 
-    it "accepts any callable object" do
-      inc = proc { |n| n + 1 }
+  it "accepts any callable object" do
+    inc = proc { |n| n + 1 }
 
-      double = Object.new
-      def double.call(n); n * 2; end
+    double = Object.new
+    def double.call(n); n * 2; end
 
-      (inc << double).call(3).should == 7
-    end
+    (inc << double).call(3).should == 7
+  end
 
-    it_behaves_like :proc_compose, :<<, -> { proc { |s| s.upcase } }
+  it_behaves_like :proc_compose, :<<, -> { proc { |s| s.upcase } }
 
-    describe "composition" do
-      it "is a Proc" do
+  describe "composition" do
+    it "is a Proc" do
+      f = proc { |x| x * x }
+      g = proc { |x| x + x }
+
+      (f << g).is_a?(Proc).should == true
+      (f << g).should_not.lambda?
+    end
+
+    ruby_version_is(''...'3.0') do
+      it "is a Proc when other is lambda" do
         f = proc { |x| x * x }
-        g = proc { |x| x + x }
+        g = -> x { x + x }
 
         (f << g).is_a?(Proc).should == true
         (f << g).should_not.lambda?
       end
 
-      ruby_version_is(''...'3.0') do
-        it "is a Proc when other is lambda" do
-          f = proc { |x| x * x }
-          g = -> x { x + x }
-
-          (f << g).is_a?(Proc).should == true
-          (f << g).should_not.lambda?
-        end
-
-        it "is a lambda when self is lambda" do
-          f = -> x { x * x }
-          g = proc { |x| x + x }
+      it "is a lambda when self is lambda" do
+        f = -> x { x * x }
+        g = proc { |x| x + x }
 
-          (f << g).is_a?(Proc).should == true
-          (f << g).should.lambda?
-        end
+        (f << g).is_a?(Proc).should == true
+        (f << g).should.lambda?
       end
+    end
 
-      ruby_version_is('3.0') do
-        it "is a lambda when parameter is lambda" do
-          f = -> x { x * x }
-          g = proc { |x| x + x }
-          lambda_proc = -> x { x }
+    ruby_version_is('3.0') do
+      it "is a lambda when parameter is lambda" do
+        f = -> x { x * x }
+        g = proc { |x| x + x }
+        lambda_proc = -> x { x }
 
-          (f << g).is_a?(Proc).should == true
-          (f << g).should_not.lambda?
-          (f << lambda_proc).should.lambda?
-        end
+        (f << g).is_a?(Proc).should == true
+        (f << g).should_not.lambda?
+        (f << lambda_proc).should.lambda?
       end
+    end
 
-      it "may accept multiple arguments" do
-        inc = proc { |n| n + 1 }
-        mul = proc { |n, m| n * m }
+    it "may accept multiple arguments" do
+      inc = proc { |n| n + 1 }
+      mul = proc { |n, m| n * m }
 
-        (inc << mul).call(2, 3).should == 7
-      end
+      (inc << mul).call(2, 3).should == 7
+    end
 
-      it "passes blocks to the second proc" do
-        ScratchPad.record []
-        one = proc { |&arg| arg.call :one if arg }
-        two = proc { |&arg| arg.call :two if arg }
-        (one << two).call { |x| ScratchPad << x }
-        ScratchPad.recorded.should == [:two]
-      end
+    it "passes blocks to the second proc" do
+      ScratchPad.record []
+      one = proc { |&arg| arg.call :one if arg }
+      two = proc { |&arg| arg.call :two if arg }
+      (one << two).call { |x| ScratchPad << x }
+      ScratchPad.recorded.should == [:two]
     end
   end
+end
 
-  describe "Proc#>>" do
-    it "returns a Proc that is the composition of self and the passed Proc" do
-      upcase = proc { |s| s.upcase }
-      succ = proc { |s| s.succ }
+describe "Proc#>>" do
+  it "returns a Proc that is the composition of self and the passed Proc" do
+    upcase = proc { |s| s.upcase }
+    succ = proc { |s| s.succ }
 
-      (succ >> upcase).call('Ruby').should == "RUBZ"
-    end
+    (succ >> upcase).call('Ruby').should == "RUBZ"
+  end
 
-    it "calls passed Proc with arguments and then calls self with result" do
-      f = proc { |x| x * x }
-      g = proc { |x| x + x }
+  it "calls passed Proc with arguments and then calls self with result" do
+    f = proc { |x| x * x }
+    g = proc { |x| x + x }
 
-      (f >> g).call(2).should == 8
-      (g >> f).call(2).should == 16
-    end
+    (f >> g).call(2).should == 8
+    (g >> f).call(2).should == 16
+  end
 
-    it "accepts any callable object" do
-      inc = proc { |n| n + 1 }
+  it "accepts any callable object" do
+    inc = proc { |n| n + 1 }
 
-      double = Object.new
-      def double.call(n); n * 2; end
+    double = Object.new
+    def double.call(n); n * 2; end
 
-      (inc >> double).call(3).should == 8
-    end
+    (inc >> double).call(3).should == 8
+  end
 
-    it_behaves_like :proc_compose, :>>, -> { proc { |s| s.upcase } }
+  it_behaves_like :proc_compose, :>>, -> { proc { |s| s.upcase } }
 
-    describe "composition" do
-      it "is a Proc" do
-        f = proc { |x| x * x }
-        g = proc { |x| x + x }
+  describe "composition" do
+    it "is a Proc" do
+      f = proc { |x| x * x }
+      g = proc { |x| x + x }
 
-        (f >> g).is_a?(Proc).should == true
-        (f >> g).should_not.lambda?
-      end
+      (f >> g).is_a?(Proc).should == true
+      (f >> g).should_not.lambda?
+    end
 
-      it "is a Proc when other is lambda" do
-        f = proc { |x| x * x }
-        g = -> x { x + x }
+    it "is a Proc when other is lambda" do
+      f = proc { |x| x * x }
+      g = -> x { x + x }
 
-        (f >> g).is_a?(Proc).should == true
-        (f >> g).should_not.lambda?
-      end
+      (f >> g).is_a?(Proc).should == true
+      (f >> g).should_not.lambda?
+    end
 
-      it "is a lambda when self is lambda" do
-        f = -> x { x * x }
-        g = proc { |x| x + x }
+    it "is a lambda when self is lambda" do
+      f = -> x { x * x }
+      g = proc { |x| x + x }
 
-        (f >> g).is_a?(Proc).should == true
-        (f >> g).should.lambda?
-      end
+      (f >> g).is_a?(Proc).should == true
+      (f >> g).should.lambda?
+    end
 
-      it "may accept multiple arguments" do
-        inc = proc { |n| n + 1 }
-        mul = proc { |n, m| n * m }
+    it "may accept multiple arguments" do
+      inc = proc { |n| n + 1 }
+      mul = proc { |n, m| n * m }
 
-        (mul >> inc).call(2, 3).should == 7
-      end
+      (mul >> inc).call(2, 3).should == 7
+    end
 
-      it "passes blocks to the first proc" do
-        ScratchPad.record []
-        one = proc { |&arg| arg.call :one if arg }
-        two = proc { |&arg| arg.call :two if arg }
-        (one >> two).call { |x| ScratchPad << x }
-        ScratchPad.recorded.should == [:one]
-      end
+    it "passes blocks to the first proc" do
+      ScratchPad.record []
+      one = proc { |&arg| arg.call :one if arg }
+      two = proc { |&arg| arg.call :two if arg }
+      (one >> two).call { |x| ScratchPad << x }
+      ScratchPad.recorded.should == [:one]
     end
   end
 end
diff --git a/spec/ruby/core/proc/shared/compose.rb b/spec/ruby/core/proc/shared/compose.rb
index 64338cada8..e3ae7f76b8 100644
--- a/spec/ruby/core/proc/shared/compose.rb
+++ b/spec/ruby/core/proc/shared/compose.rb
@@ -1,5 +1,5 @@
 describe :proc_compose, shared: true do
-  ruby_version_is "2.6"..."2.7" do
+  ruby_version_is ""..."2.7" do
     it "raises NoMethodError when called if passed not callable object" do
       not_callable = Object.new
       composed = @object.call.send(@method, not_callable)
diff --git a/spec/ruby/core/process/spawn_spec.rb b/spec/ruby/core/process/spawn_spec.rb
index e373d8600c..56e02ff38a 100644
--- a/spec/ruby/core/process/spawn_spec.rb
+++ b/spec/ruby/core/process/spawn_spec.rb
@@ -551,27 +551,14 @@ describe "Process.spawn" do
 
   platform_is_not :windows do
     context "defaults :close_others to" do
-      ruby_version_is ""..."2.6" do
-        it "true" do
-          IO.pipe do |r, w|
-            w.close_on_exec = false
-            code = "begin; IO.new(#{w.fileno}).close; rescue Errno::EBADF; puts 'not inherited'; end"
-            Process.wait Process.spawn(ruby_cmd(code), :out => @name)
-            File.read(@name).should == "not inherited\n"
-          end
-        end
-      end
-
-      ruby_version_is "2.6" do
-        it "false" do
-          IO.pipe do |r, w|
-            w.close_on_exec = false
-            code = "io = IO.new(#{w.fileno}); io.puts('inherited'); io.close"
-            pid = Process.spawn(ruby_cmd(code))
-            w.close
-            Process.wait(pid)
-            r.read.should == "inherited\n"
-          end
+      it "false" do
+        IO.pipe do |r, w|
+          w.close_on_exec = false
+          code = "io = IO.new(#{w.fileno}); io.puts('inherited'); io.close"
+          pid = Process.spawn(ruby_cmd(code))
+          w.close
+          Process.wait(pid)
+          r.read.should == "inherited\n"
         end
       end
     end
diff --git a/spec/ruby/core/process/status/wait_spec.rb b/spec/ruby/core/process/status/wait_spec.rb
new file mode 100644
index 0000000000..b9d80e31f4
--- /dev/null
+++ b/spec/ruby/core/process/status/wait_spec.rb
@@ -0,0 +1,102 @@
+require_relative '../../../spec_helper'
+require_relative '../fixtures/common'
+
+ruby_version_is "3.0" do
+  describe "Process::Status.wait" do
+    ProcessSpecs.use_system_ruby(self)
+
+    before :all do
+      begin
+        leaked = Process.waitall
+        # Ruby-space should not see PIDs used by mjit
+        raise "subprocesses leaked before wait specs: #{leaked}" unless leaked.empty?
+      rescue NotImplementedError
+      end
+    end
+
+    it "returns a status with pid -1 if there are no child processes" do
+      Process::Status.wait.pid.should == -1
+    end
+
+    platform_is_not :windows do
+      it "returns a status with its child pid" do
+        pid = Process.spawn(ruby_cmd('exit'))
+        status = Process::Status.wait
+        status.should be_an_instance_of(Process::Status)
+        status.pid.should == pid
+      end
+
+      it "should not set $? to the Process::Status" do
+        pid = Process.spawn(ruby_cmd('exit'))
+        status = Process::Status.wait
+        $?.should_not equal(status)
+      end
+
+      it "should not change the value of $?" do
+        pid = Process.spawn(ruby_cmd('exit'))
+        Process.wait
+        status = $?
+        Process::Status.wait
+        status.should equal($?)
+      end
+
+      it "waits for any child process if no pid is given" do
+        pid = Process.spawn(ruby_cmd('exit'))
+        Process::Status.wait.pid.should == pid
+        -> { Process.kill(0, pid) }.should raise_error(Errno::ESRCH)
+      end
+
+      it "waits for a specific child if a pid is given" do
+        pid1 = Process.spawn(ruby_cmd('exit'))
+        pid2 = Process.spawn(ruby_cmd('exit'))
+        Process::Status.wait(pid2).pid.should == pid2
+        Process::Status.wait(pid1).pid.should == pid1
+        -> { Process.kill(0, pid1) }.should raise_error(Errno::ESRCH)
+        -> { Process.kill(0, pid2) }.should raise_error(Errno::ESRCH)
+      end
+
+      it "coerces the pid to an Integer" do
+        pid1 = Process.spawn(ruby_cmd('exit'))
+        Process::Status.wait(mock_int(pid1)).pid.should == pid1
+        -> { Process.kill(0, pid1) }.should raise_error(Errno::ESRCH)
+      end
+
+      # This spec is probably system-dependent.
+      it "waits for a child whose process group ID is that of the calling process" do
+        pid1 = Process.spawn(ruby_cmd('exit'), pgroup: true)
+        pid2 = Process.spawn(ruby_cmd('exit'))
+
+        Process::Status.wait(0).pid.should == pid2
+        Process::Status.wait.pid.should == pid1
+      end
+
+      # This spec is probably system-dependent.
+      it "doesn't block if no child is available when WNOHANG is used" do
+        read, write = IO.pipe
+        pid = Process.fork do
+          read.close
+          Signal.trap("TERM") { Process.exit! }
+          write << 1
+          write.close
+          sleep
+        end
+
+        Process::Status.wait(pid, Process::WNOHANG).should be_nil
+
+        # wait for the child to setup its TERM handler
+        write.close
+        read.read(1)
+        read.close
+
+        Process.kill("TERM", pid)
+        Process::Status.wait.pid.should == pid
+      end
+
+      it "always accepts flags=0" do
+        pid = Process.spawn(ruby_cmd('exit'))
+        Process::Status.wait(-1, 0).pid.should == pid
+        -> { Process.kill(0, pid) }.should raise_error(Errno::ESRCH)
+      end
+    end
+  end
+end
diff --git a/spec/ruby/core/random/bytes_spec.rb b/spec/ruby/core/random/bytes_spec.rb
index 2caf18fbd0..06e84d03bd 100644
--- a/spec/ruby/core/random/bytes_spec.rb
+++ b/spec/ruby/core/random/bytes_spec.rb
@@ -25,8 +25,6 @@ describe "Random#bytes" do
   end
 end
 
-ruby_version_is "2.6" do
-  describe "Random.bytes" do
-    it_behaves_like :random_bytes, :bytes, Random
-  end
+describe "Random.bytes" do
+  it_behaves_like :random_bytes, :bytes, Random
 end
diff --git a/spec/ruby/core/random/random_number_spec.rb b/spec/ruby/core/random/random_number_spec.rb
index 60a80ae1b9..bad81aeff6 100644
--- a/spec/ruby/core/random/random_number_spec.rb
+++ b/spec/ruby/core/random/random_number_spec.rb
@@ -4,7 +4,5 @@ require_relative 'shared/rand'
 describe "Random.random_number" do
   it_behaves_like :random_number, :random_number, Random.new
 
-  ruby_version_is "2.6" do
-    it_behaves_like :random_number, :random_number, Random
-  end
+  it_behaves_like :random_number, :random_number, Random
 end
diff --git a/spec/ruby/core/range/bsearch_spec.rb b/spec/ruby/core/range/bsearch_spec.rb
index d31c5d5d51..438c7ce314 100644
--- a/spec/ruby/core/range/bsearch_spec.rb
+++ b/spec/ruby/core/range/bsearch_spec.rb
@@ -215,118 +215,116 @@ describe "Range#bsearch" do
     end
   end
 
-  ruby_version_is "2.6" do
-    context "with endless ranges and Integer values" do
-      context "with a block returning true or false" do
-        it "returns minimum element if the block returns true for every element" do
-          eval("(-2..)").bsearch { |x| true }.should == -2
-        end
+  context "with endless ranges and Integer values" do
+    context "with a block returning true or false" do
+      it "returns minimum element if the block returns true for every element" do
+        eval("(-2..)").bsearch { |x| true }.should == -2
+      end
 
-        it "returns the smallest element for which block returns true" do
-          eval("(0..)").bsearch { |x| x >= 2 }.should == 2
-          eval("(-1..)").bsearch { |x| x >= 1 }.should == 1
-        end
+      it "returns the smallest element for which block returns true" do
+        eval("(0..)").bsearch { |x| x >= 2 }.should == 2
+        eval("(-1..)").bsearch { |x| x >= 1 }.should == 1
       end
+    end
 
-      context "with a block returning negative, zero, positive numbers" do
-        it "returns nil if the block returns less than zero for every element" do
-          eval("(0..)").bsearch { |x| -1 }.should be_nil
-        end
+    context "with a block returning negative, zero, positive numbers" do
+      it "returns nil if the block returns less than zero for every element" do
+        eval("(0..)").bsearch { |x| -1 }.should be_nil
+      end
 
-        it "returns nil if the block never returns zero" do
-          eval("(0..)").bsearch { |x| x > 5 ? -1 : 1 }.should be_nil
-        end
+      it "returns nil if the block never returns zero" do
+        eval("(0..)").bsearch { |x| x > 5 ? -1 : 1 }.should be_nil
+      end
 
-        it "accepts -Float::INFINITY from the block" do
-          eval("(0..)").bsearch { |x| -Float::INFINITY }.should be_nil
-        end
+      it "accepts -Float::INFINITY from the block" do
+        eval("(0..)").bsearch { |x| -Float::INFINITY }.should be_nil
+      end
 
-        it "returns an element at an index for which block returns 0.0" do
-          result = eval("(0..)").bsearch { |x| x < 2 ? 1.0 : x > 2 ? -1.0 : 0.0 }
-          result.should == 2
-        end
+      it "returns an element at an index for which block returns 0.0" do
+        result = eval("(0..)").bsearch { |x| x < 2 ? 1.0 : x > 2 ? -1.0 : 0.0 }
+        result.should == 2
+      end
 
-        it "returns an element at an index for which block returns 0" do
-          result = eval("(0..)").bsearch { |x| x < 1 ? 1 : x > 3 ? -1 : 0 }
-          [1, 2, 3].should include(result)
-        end
+      it "returns an element at an index for which block returns 0" do
+        result = eval("(0..)").bsearch { |x| x < 1 ? 1 : x > 3 ? -1 : 0 }
+        [1, 2, 3].should include(result)
       end
     end
+  end
 
-    context "with endless ranges and Float values" do
-      context "with a block returning true or false" do
-        it "returns nil if the block returns false for every element" do
-          eval("(0.1..)").bsearch { |x| x < 0.0 }.should be_nil
-          eval("(0.1...)").bsearch { |x| x < 0.0 }.should be_nil
-        end
+  context "with endless ranges and Float values" do
+    context "with a block returning true or false" do
+      it "returns nil if the block returns false for every element" do
+        eval("(0.1..)").bsearch { |x| x < 0.0 }.should be_nil
+        eval("(0.1...)").bsearch { |x| x < 0.0 }.should be_nil
+      end
 
-        it "returns nil if the block returns nil for every element" do
-          eval("(-0.0..)").bsearch { |x| nil }.should be_nil
-          eval("(-0.0...)").bsearch { |x| nil }.should be_nil
-        end
+      it "returns nil if the block returns nil for every element" do
+        eval("(-0.0..)").bsearch { |x| nil }.should be_nil
+        eval("(-0.0...)").bsearch { |x| nil }.should be_nil
+      end
 
-        it "returns minimum element if the block returns true for every element" do
-          eval("(-0.2..)").bsearch { |x| true }.should == -0.2
-          eval("(-0.2...)").bsearch { |x| true }.should == -0.2
-        end
+      it "returns minimum element if the block returns true for every element" do
+        eval("(-0.2..)").bsearch { |x| true }.should == -0.2
+        eval("(-0.2...)").bsearch { |x| true }.should == -0.2
+      end
 
-        it "returns the smallest element for which block returns true" do
-          eval("(0..)").bsearch { |x| x >= 2 }.should == 2
-          eval("(-1.2..)").bsearch { |x| x >= 1 }.should == 1
-        end
+      it "returns the smallest element for which block returns true" do
+        eval("(0..)").bsearch { |x| x >= 2 }.should == 2
+        eval("(-1.2..)").bsearch { |x| x >= 1 }.should == 1
+      end
 
-        it "works with infinity bounds" do
-          inf = Float::INFINITY
-          eval("(inf..)").bsearch { |x| true }.should == inf
-          eval("(inf...)").bsearch { |x| true }.should == nil
-          eval("(-inf..)").bsearch { |x| true }.should == -inf
-          eval("(-inf...)").bsearch { |x| true }.should == -inf
-        end
+      it "works with infinity bounds" do
+        inf = Float::INFINITY
+        eval("(inf..)").bsearch { |x| true }.should == inf
+        eval("(inf...)").bsearch { |x| true }.should == nil
+        eval("(-inf..)").bsearch { |x| true }.should == -inf
+        eval("(-inf...)").bsearch { |x| true }.should == -inf
       end
+    end
 
-      context "with a block returning negative, zero, positive numbers" do
-        it "returns nil if the block returns less than zero for every element" do
-          eval("(-2.0..)").bsearch { |x| -1 }.should be_nil
-          eval("(-2.0...)").bsearch { |x| -1 }.should be_nil
-        end
+    context "with a block returning negative, zero, positive numbers" do
+      it "returns nil if the block returns less than zero for every element" do
+        eval("(-2.0..)").bsearch { |x| -1 }.should be_nil
+        eval("(-2.0...)").bsearch { |x| -1 }.should be_nil
+      end
 
-        it "returns nil if the block returns greater than zero for every element" do
-          eval("(0.3..)").bsearch { |x| 1 }.should be_nil
-          eval("(0.3...)").bsearch { |x| 1 }.should be_nil
-        end
+      it "returns nil if the block returns greater than zero for every element" do
+        eval("(0.3..)").bsearch { |x| 1 }.should be_nil
+        eval("(0.3...)").bsearch { |x| 1 }.should be_nil
+      end
 
-        it "returns nil if the block never returns zero" do
-          eval("(0.2..)").bsearch { |x| x < 2 ? 1 : -1 }.should be_nil
-        end
+      it "returns nil if the block never returns zero" do
+        eval("(0.2..)").bsearch { |x| x < 2 ? 1 : -1 }.should be_nil
+      end
 
-        it "accepts (+/-)Float::INFINITY from the block" do
-          eval("(0.1..)").bsearch { |x| Float::INFINITY }.should be_nil
-          eval("(-5.0..)").bsearch { |x| -Float::INFINITY }.should be_nil
-        end
+      it "accepts (+/-)Float::INFINITY from the block" do
+        eval("(0.1..)").bsearch { |x| Float::INFINITY }.should be_nil
+        eval("(-5.0..)").bsearch { |x| -Float::INFINITY }.should be_nil
+      end
 
-        it "returns an element at an index for which block returns 0.0" do
-          result = eval("(0.0..)").bsearch { |x| x < 2 ? 1.0 : x > 2 ? -1.0 : 0.0 }
-          result.should == 2
-        end
+      it "returns an element at an index for which block returns 0.0" do
+        result = eval("(0.0..)").bsearch { |x| x < 2 ? 1.0 : x > 2 ? -1.0 : 0.0 }
+        result.should == 2
+      end
 
-        it "returns an element at an index for which block returns 0" do
-          result = eval("(0.1..)").bsearch { |x| x < 1 ? 1 : x > 3 ? -1 : 0 }
-          result.should >= 1
-          result.should <= 3
-        end
+      it "returns an element at an index for which block returns 0" do
+        result = eval("(0.1..)").bsearch { |x| x < 1 ? 1 : x > 3 ? -1 : 0 }
+        result.should >= 1
+        result.should <= 3
+      end
 
-        it "works with infinity bounds" do
-          inf = Float::INFINITY
-          eval("(inf..)").bsearch { |x| 1 }.should == nil
-          eval("(inf...)").bsearch { |x| 1 }.should == nil
-          eval("(inf..)").bsearch { |x| x == inf ? 0 : 1 }.should == inf
-          eval("(inf...)").bsearch { |x| x == inf ? 0 : 1 }.should == nil
-          eval("(-inf..)").bsearch { |x| x == -inf ? 0 : -1 }.should == -inf
-          eval("(-inf...)").bsearch { |x| x == -inf ? 0 : -1 }.should == -inf
-          eval("(-inf..)").bsearch { |x| 3 - x }.should == 3
-          eval("(-inf...)").bsearch { |x| 3 - x }.should == 3
-          eval("(0.0...)").bsearch { 0 }.should != inf
-        end
+      it "works with infinity bounds" do
+        inf = Float::INFINITY
+        eval("(inf..)").bsearch { |x| 1 }.should == nil
+        eval("(inf...)").bsearch { |x| 1 }.should == nil
+        eval("(inf..)").bsearch { |x| x == inf ? 0 : 1 }.should == inf
+        eval("(inf...)").bsearch { |x| x == inf ? 0 : 1 }.should == nil
+        eval("(-inf..)").bsearch { |x| x == -inf ? 0 : -1 }.should == -inf
+        eval("(-inf...)").bsearch { |x| x == -inf ? 0 : -1 }.should == -inf
+        eval("(-inf..)").bsearch { |x| 3 - x }.should == 3
+        eval("(-inf...)").bsearch { |x| 3 - x }.should == 3
+        eval("(0.0...)").bsearch { 0 }.should != inf
       end
     end
   end
diff --git a/spec/ruby/core/range/case_compare_spec.rb b/spec/ruby/core/range/case_compare_spec.rb
index b1afa90a41..e795026230 100644
--- a/spec/ruby/core/range/case_compare_spec.rb
+++ b/spec/ruby/core/range/case_compare_spec.rb
@@ -3,27 +3,9 @@ require_relative 'shared/cover_and_include'
 require_relative 'shared/cover'
 
 describe "Range#===" do
-  ruby_version_is ""..."2.6" do
-    it "returns the result of calling #include? on self" do
-      range = 0...10
-      range.should_receive(:include?).with(2).and_return(:true)
-      (range === 2).should == :true
-    end
-
-    it "requires #succ method to be implemented" do
-      range = RangeSpecs::WithoutSucc.new(0)..RangeSpecs::WithoutSucc.new(10)
-
-      -> do
-        range === RangeSpecs::WithoutSucc.new(2)
-      end.should raise_error(TypeError, /can't iterate from/)
-    end
-  end
-
-  ruby_version_is "2.6" do
-    it "returns the result of calling #cover? on self" do
-      range = RangeSpecs::WithoutSucc.new(0)..RangeSpecs::WithoutSucc.new(10)
-      (range === RangeSpecs::WithoutSucc.new(2)).should == true
-    end
+  it "returns the result of calling #cover? on self" do
+    range = RangeSpecs::WithoutSucc.new(0)..RangeSpecs::WithoutSucc.new(10)
+    (range === RangeSpecs::WithoutSucc.new(2)).should == true
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/range/each_spec.rb b/spec/ruby/core/range/each_spec.rb
index 1dce9c1f1e..bd4bbb82e5 100644
--- a/spec/ruby/core/range/each_spec.rb
+++ b/spec/ruby/core/range/each_spec.rb
@@ -38,26 +38,24 @@ describe "Range#each" do
     a.should == ["Σ", "Τ", "Υ", "Φ", "Χ", "Ψ", "Ω"]
   end
 
-  ruby_version_is "2.6" do
-    it "works with endless ranges" do
-      a = []
-      eval("(-2..)").each { |x| break if x > 2; a << x }
-      a.should == [-2, -1, 0, 1, 2]
-
-      a = []
-      eval("(-2...)").each { |x| break if x > 2; a << x }
-      a.should == [-2, -1, 0, 1, 2]
-    end
+  it "works with endless ranges" do
+    a = []
+    eval("(-2..)").each { |x| break if x > 2; a << x }
+    a.should == [-2, -1, 0, 1, 2]
+
+    a = []
+    eval("(-2...)").each { |x| break if x > 2; a << x }
+    a.should == [-2, -1, 0, 1, 2]
+  end
 
-    it "works with String endless ranges" do
-      a = []
-      eval("('A'..)").each { |x| break if x > "D"; a << x }
-      a.should == ["A", "B", "C", "D"]
+  it "works with String endless ranges" do
+    a = []
+    eval("('A'..)").each { |x| break if x > "D"; a << x }
+    a.should == ["A", "B", "C", "D"]
 
-      a = []
-      eval("('A'...)").each { |x| break if x > "D"; a << x }
-      a.should == ["A", "B", "C", "D"]
-    end
+    a = []
+    eval("('A'...)").each { |x| break if x > "D"; a << x }
+    a.should == ["A", "B", "C", "D"]
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/range/equal_value_spec.rb b/spec/ruby/core/range/equal_value_spec.rb
index f88d3029bb..0aaebfb59a 100644
--- a/spec/ruby/core/range/equal_value_spec.rb
+++ b/spec/ruby/core/range/equal_value_spec.rb
@@ -8,10 +8,8 @@ describe "Range#==" do
     (0..1).should == (0..1.0)
   end
 
-  ruby_version_is "2.6" do
-    it "returns true if the endpoints are == for endless ranges" do
-      eval("(1.0..)").should == eval("(1.0..)")
-    end
+  it "returns true if the endpoints are == for endless ranges" do
+    eval("(1.0..)").should == eval("(1.0..)")
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/range/inspect_spec.rb b/spec/ruby/core/range/inspect_spec.rb
index 6a206a0355..f49882e6ce 100644
--- a/spec/ruby/core/range/inspect_spec.rb
+++ b/spec/ruby/core/range/inspect_spec.rb
@@ -12,11 +12,9 @@ describe "Range#inspect" do
     (0.5..2.4).inspect.should == "0.5..2.4"
   end
 
-  ruby_version_is "2.6" do
-    it "works for endless ranges" do
-      eval("(1..)").inspect.should ==  "1.."
-      eval("(0.1...)").inspect.should ==  "0.1..."
-    end
+  it "works for endless ranges" do
+    eval("(1..)").inspect.should ==  "1.."
+    eval("(0.1...)").inspect.should ==  "0.1..."
   end
 
   ruby_version_is '2.7' do
diff --git a/spec/ruby/core/range/last_spec.rb b/spec/ruby/core/range/last_spec.rb
index 54884ba4d6..d7ef776b42 100644
--- a/spec/ruby/core/range/last_spec.rb
+++ b/spec/ruby/core/range/last_spec.rb
@@ -47,9 +47,7 @@ describe "Range#last" do
     -> { (2..3).last("1") }.should raise_error(TypeError)
   end
 
-  ruby_version_is "2.6" do
-    it "raises a RangeError when called on an endless range" do
-      -> { eval("(1..)").last }.should raise_error(RangeError)
-    end
+  it "raises a RangeError when called on an endless range" do
+    -> { eval("(1..)").last }.should raise_error(RangeError)
   end
 end
diff --git a/spec/ruby/core/range/max_spec.rb b/spec/ruby/core/range/max_spec.rb
index f2672170d9..a970144d66 100644
--- a/spec/ruby/core/range/max_spec.rb
+++ b/spec/ruby/core/range/max_spec.rb
@@ -46,10 +46,8 @@ describe "Range#max" do
     -> { (time_start...time_end).max  }.should raise_error(TypeError)
   end
 
-  ruby_version_is "2.6" do
-    it "raises RangeError when called on an endless range" do
-      -> { eval("(1..)").max }.should raise_error(RangeError)
-    end
+  it "raises RangeError when called on an endless range" do
+    -> { eval("(1..)").max }.should raise_error(RangeError)
   end
 
   ruby_version_is "3.0" do
diff --git a/spec/ruby/core/range/min_spec.rb b/spec/ruby/core/range/min_spec.rb
index ffd40f3a07..6e56cc733b 100644
--- a/spec/ruby/core/range/min_spec.rb
+++ b/spec/ruby/core/range/min_spec.rb
@@ -39,11 +39,9 @@ describe "Range#min" do
     (time_start...time_end).min.should equal(time_start)
   end
 
-  ruby_version_is "2.6" do
-    it "returns the start point for endless ranges" do
-      eval("(1..)").min.should == 1
-      eval("(1.0...)").min.should == 1.0
-    end
+  it "returns the start point for endless ranges" do
+    eval("(1..)").min.should == 1
+    eval("(1.0...)").min.should == 1.0
   end
 
   ruby_version_is "2.7" do
@@ -86,9 +84,7 @@ describe "Range#min given a block" do
     (7...7).min {|x,y| x <=> y}.should be_nil
   end
 
-  ruby_version_is "2.6" do
-    it "raises RangeError when called with custom comparison method on an endless range" do
-      -> { eval("(1..)").min {|a, b| a} }.should raise_error(RangeError)
-    end
+  it "raises RangeError when called with custom comparison method on an endless range" do
+    -> { eval("(1..)").min {|a, b| a} }.should raise_error(RangeError)
   end
 end
diff --git a/spec/ruby/core/range/minmax_spec.rb b/spec/ruby/core/range/minmax_spec.rb
index fa0637ac56..1db9bfce38 100644
--- a/spec/ruby/core/range/minmax_spec.rb
+++ b/spec/ruby/core/range/minmax_spec.rb
@@ -1,6 +1,6 @@
 require_relative '../../spec_helper'
 
-# These specs use Range.new instead of the literal notation so they parse fine on Ruby < 2.6
+# These specs use Range.new instead of the literal notation for beginless Ranges so they parse fine on Ruby < 2.7
 describe 'Range#minmax' do
   before(:each) do
     @x = mock('x')
@@ -13,10 +13,10 @@ describe 'Range#minmax' do
   end
 
   describe 'on an inclusive range' do
-    ruby_version_is '2.6'...'2.7' do
+    ruby_version_is ''...'2.7' do
       it 'should try to iterate endlessly on an endless range' do
         @x.should_receive(:succ).once.and_return(@y)
-        range = Range.new(@x, nil)
+        range = (@x..)
 
         -> { range.minmax }.should raise_error(NoMethodError, /^undefined method `succ' for/)
       end
@@ -26,7 +26,7 @@ describe 'Range#minmax' do
       it 'should raise RangeError on an endless range without iterating the range' do
         @x.should_not_receive(:succ)
 
-        range = Range.new(@x, nil)
+        range = (@x..)
 
         -> { range.minmax }.should raise_error(RangeError, 'cannot get the maximum of endless range')
       end
@@ -96,11 +96,11 @@ describe 'Range#minmax' do
   end
 
   describe 'on an exclusive range' do
-    ruby_version_is '2.6'...'2.7' do
+    ruby_version_is ''...'2.7' do
       # Endless ranges introduced in 2.6
       it 'should try to iterate endlessly on an endless range' do
         @x.should_receive(:succ).once.and_return(@y)
-        range = Range.new(@x, nil, true)
+        range = (@x...)
 
         -> { range.minmax }.should raise_error(NoMethodError, /^undefined method `succ' for/)
       end
@@ -109,7 +109,7 @@ describe 'Range#minmax' do
     ruby_version_is '2.7' do
       it 'should raise RangeError on an endless range' do
         @x.should_not_receive(:succ)
-        range = Range.new(@x, nil, true)
+        range = (@x...)
 
         -> { range.minmax }.should raise_error(RangeError, 'cannot get the maximum of endless range')
       end
diff --git a/spec/ruby/core/range/new_spec.rb b/spec/ruby/core/range/new_spec.rb
index be10ff244e..a4de4963e7 100644
--- a/spec/ruby/core/range/new_spec.rb
+++ b/spec/ruby/core/range/new_spec.rb
@@ -62,24 +62,16 @@ describe "Range.new" do
       end
     end
 
-    ruby_version_is ""..."2.6" do
-      it "does not allow range without right boundary" do
-        -> { Range.new(1, nil) }.should raise_error(ArgumentError, /bad value for range/)
-      end
+    it "allows endless right boundary" do
+      range = Range.new(1, nil)
+      range.end.should == nil
     end
 
-    ruby_version_is "2.6" do
-      it "allows endless right boundary" do
-        range = Range.new(1, nil)
-        range.end.should == nil
-      end
-
-      it "distinguishes ranges with included and excluded right boundary" do
-        range_exclude = Range.new(1, nil, true)
-        range_include = Range.new(1, nil, false)
+    it "distinguishes ranges with included and excluded right boundary" do
+      range_exclude = Range.new(1, nil, true)
+      range_include = Range.new(1, nil, false)
 
-        range_exclude.should_not == range_include
-      end
+      range_exclude.should_not == range_include
     end
   end
 end
diff --git a/spec/ruby/core/range/percent_spec.rb b/spec/ruby/core/range/percent_spec.rb
index 41badd4f72..5ec6770ddb 100644
--- a/spec/ruby/core/range/percent_spec.rb
+++ b/spec/ruby/core/range/percent_spec.rb
@@ -1,18 +1,16 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "2.6" do
-  describe "Range#%" do
-    it "works as a Range#step" do
-      aseq = (1..10) % 2
-      aseq.class.should == Enumerator::ArithmeticSequence
-      aseq.begin.should == 1
-      aseq.end.should == 10
-      aseq.step.should == 2
-      aseq.to_a.should == [1, 3, 5, 7, 9]
-    end
+describe "Range#%" do
+  it "works as a Range#step" do
+    aseq = (1..10) % 2
+    aseq.class.should == Enumerator::ArithmeticSequence
+    aseq.begin.should == 1
+    aseq.end.should == 10
+    aseq.step.should == 2
+    aseq.to_a.should == [1, 3, 5, 7, 9]
+  end
 
-    it "produces an arithmetic sequence with a percent sign in #inspect" do
-      ((1..10) % 2).inspect.should == "((1..10).%(2))"
-    end
+  it "produces an arithmetic sequence with a percent sign in #inspect" do
+    ((1..10) % 2).inspect.should == "((1..10).%(2))"
   end
 end
diff --git a/spec/ruby/core/range/shared/cover.rb b/spec/ruby/core/range/shared/cover.rb
index e04682ba71..f3c7d22668 100644
--- a/spec/ruby/core/range/shared/cover.rb
+++ b/spec/ruby/core/range/shared/cover.rb
@@ -93,63 +93,61 @@ describe :range_cover, shared: true do
 end
 
 describe :range_cover_subrange, shared: true do
-  ruby_version_is "2.6" do
-    context "range argument" do
-      it "accepts range argument" do
-        (0..10).send(@method, (3..7)).should be_true
-        (0..10).send(@method, (3..15)).should be_false
-        (0..10).send(@method, (-2..7)).should be_false
-
-        (1.1..7.9).send(@method, (2.5..6.5)).should be_true
-        (1.1..7.9).send(@method, (2.5..8.5)).should be_false
-        (1.1..7.9).send(@method, (0.5..6.5)).should be_false
-
-        ('c'..'i').send(@method, ('d'..'f')).should be_true
-        ('c'..'i').send(@method, ('d'..'z')).should be_false
-        ('c'..'i').send(@method, ('a'..'f')).should be_false
-
-        range_10_100 = RangeSpecs::TenfoldSucc.new(10)..RangeSpecs::TenfoldSucc.new(100)
-        range_20_90 = RangeSpecs::TenfoldSucc.new(20)..RangeSpecs::TenfoldSucc.new(90)
-        range_20_110 = RangeSpecs::TenfoldSucc.new(20)..RangeSpecs::TenfoldSucc.new(110)
-        range_0_90 = RangeSpecs::TenfoldSucc.new(0)..RangeSpecs::TenfoldSucc.new(90)
-
-        range_10_100.send(@method, range_20_90).should be_true
-        range_10_100.send(@method, range_20_110).should be_false
-        range_10_100.send(@method, range_0_90).should be_false
-      end
+  context "range argument" do
+    it "accepts range argument" do
+      (0..10).send(@method, (3..7)).should be_true
+      (0..10).send(@method, (3..15)).should be_false
+      (0..10).send(@method, (-2..7)).should be_false
+
+      (1.1..7.9).send(@method, (2.5..6.5)).should be_true
+      (1.1..7.9).send(@method, (2.5..8.5)).should be_false
+      (1.1..7.9).send(@method, (0.5..6.5)).should be_false
+
+      ('c'..'i').send(@method, ('d'..'f')).should be_true
+      ('c'..'i').send(@method, ('d'..'z')).should be_false
+      ('c'..'i').send(@method, ('a'..'f')).should be_false
+
+      range_10_100 = RangeSpecs::TenfoldSucc.new(10)..RangeSpecs::TenfoldSucc.new(100)
+      range_20_90 = RangeSpecs::TenfoldSucc.new(20)..RangeSpecs::TenfoldSucc.new(90)
+      range_20_110 = RangeSpecs::TenfoldSucc.new(20)..RangeSpecs::TenfoldSucc.new(110)
+      range_0_90 = RangeSpecs::TenfoldSucc.new(0)..RangeSpecs::TenfoldSucc.new(90)
+
+      range_10_100.send(@method, range_20_90).should be_true
+      range_10_100.send(@method, range_20_110).should be_false
+      range_10_100.send(@method, range_0_90).should be_false
+    end
 
-      it "supports boundaries of different comparable types" do
-        (0..10).send(@method, (3.1..7.9)).should be_true
-        (0..10).send(@method, (3.1..15.9)).should be_false
-        (0..10).send(@method, (-2.1..7.9)).should be_false
-      end
+    it "supports boundaries of different comparable types" do
+      (0..10).send(@method, (3.1..7.9)).should be_true
+      (0..10).send(@method, (3.1..15.9)).should be_false
+      (0..10).send(@method, (-2.1..7.9)).should be_false
+    end
 
-      it "returns false if types are not comparable" do
-        (0..10).send(@method, ('a'..'z')).should be_false
-        (0..10).send(@method, (RangeSpecs::TenfoldSucc.new(0)..RangeSpecs::TenfoldSucc.new(100))).should be_false
-      end
+    it "returns false if types are not comparable" do
+      (0..10).send(@method, ('a'..'z')).should be_false
+      (0..10).send(@method, (RangeSpecs::TenfoldSucc.new(0)..RangeSpecs::TenfoldSucc.new(100))).should be_false
+    end
 
-      it "honors exclusion of right boundary (:exclude_end option)" do
-        # Integer
-        (0..10).send(@method, (0..10)).should be_true
-        (0...10).send(@method, (0...10)).should be_true
+    it "honors exclusion of right boundary (:exclude_end option)" do
+      # Integer
+      (0..10).send(@method, (0..10)).should be_true
+      (0...10).send(@method, (0...10)).should be_true
 
-        (0..10).send(@method, (0...10)).should be_true
-        (0...10).send(@method, (0..10)).should be_false
+      (0..10).send(@method, (0...10)).should be_true
+      (0...10).send(@method, (0..10)).should be_false
 
-        (0...11).send(@method, (0..10)).should be_true
-        (0..10).send(@method, (0...11)).should be_true
+      (0...11).send(@method, (0..10)).should be_true
+      (0..10).send(@method, (0...11)).should be_true
 
-        # Float
-        (0..10.1).send(@method, (0..10.1)).should be_true
-        (0...10.1).send(@method, (0...10.1)).should be_true
+      # Float
+      (0..10.1).send(@method, (0..10.1)).should be_true
+      (0...10.1).send(@method, (0...10.1)).should be_true
 
-        (0..10.1).send(@method, (0...10.1)).should be_true
-        (0...10.1).send(@method, (0..10.1)).should be_false
+      (0..10.1).send(@method, (0...10.1)).should be_true
+      (0...10.1).send(@method, (0..10.1)).should be_false
 
-        (0...11.1).send(@method, (0..10.1)).should be_true
-        (0..10.1).send(@method, (0...11.1)).should be_false
-      end
+      (0...11.1).send(@method, (0..10.1)).should be_true
+      (0..10.1).send(@method, (0...11.1)).should be_false
     end
   end
 
diff --git a/spec/ruby/core/range/shared/cover_and_include.rb b/spec/ruby/core/range/shared/cover_and_include.rb
index 0267e3ccb0..e978e39af5 100644
--- a/spec/ruby/core/range/shared/cover_and_include.rb
+++ b/spec/ruby/core/range/shared/cover_and_include.rb
@@ -19,11 +19,9 @@ describe :range_cover_and_include, shared: true do
     (0.5...2.4).send(@method, 2.4).should == false
   end
 
-  ruby_version_is "2.6" do
-    it "returns true if other is an element of self for endless ranges" do
-      eval("(1..)").send(@method, 2.4).should == true
-      eval("(0.5...)").send(@method, 2.4).should == true
-    end
+  it "returns true if other is an element of self for endless ranges" do
+    eval("(1..)").send(@method, 2.4).should == true
+    eval("(0.5...)").send(@method, 2.4).should == true
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/range/shared/equal_value.rb b/spec/ruby/core/range/shared/equal_value.rb
index 8872b4efc0..363c6be558 100644
--- a/spec/ruby/core/range/shared/equal_value.rb
+++ b/spec/ruby/core/range/shared/equal_value.rb
@@ -43,11 +43,9 @@ describe :range_eql, shared: true do
     a.send(@method, b).should == true
   end
 
-  ruby_version_is "2.6" do
-    it "works for endless Ranges" do
-      eval("(1..)").send(@method, eval("(1..)")).should == true
-      eval("(0.5...)").send(@method, eval("(0.5...)")).should == true
-      eval("(1..)").send(@method, eval("(1...)")).should == false
-    end
+  it "works for endless Ranges" do
+    eval("(1..)").send(@method, eval("(1..)")).should == true
+    eval("(0.5...)").send(@method, eval("(0.5...)")).should == true
+    eval("(1..)").send(@method, eval("(1...)")).should == false
   end
 end
diff --git a/spec/ruby/core/range/size_spec.rb b/spec/ruby/core/range/size_spec.rb
index 4bf525e541..0019c5ff00 100644
--- a/spec/ruby/core/range/size_spec.rb
+++ b/spec/ruby/core/range/size_spec.rb
@@ -24,16 +24,14 @@ describe "Range#size" do
     (-Float::INFINITY..Float::INFINITY).size.should == Float::INFINITY
   end
 
-  ruby_version_is "2.6" do
-    it 'returns Float::INFINITY for endless ranges if the start is numeric' do
-      eval("(1..)").size.should == Float::INFINITY
-      eval("(0.5...)").size.should == Float::INFINITY
-    end
+  it 'returns Float::INFINITY for endless ranges if the start is numeric' do
+    eval("(1..)").size.should == Float::INFINITY
+    eval("(0.5...)").size.should == Float::INFINITY
+  end
 
-    it 'returns nil for endless ranges if the start is not numeric' do
-      eval("('z'..)").size.should == nil
-      eval("([]...)").size.should == nil
-    end
+  it 'returns nil for endless ranges if the start is not numeric' do
+    eval("('z'..)").size.should == nil
+    eval("([]...)").size.should == nil
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/range/step_spec.rb b/spec/ruby/core/range/step_spec.rb
index be4b482654..624fa71f5f 100644
--- a/spec/ruby/core/range/step_spec.rb
+++ b/spec/ruby/core/range/step_spec.rb
@@ -282,98 +282,96 @@ describe "Range#step" do
     end
   end
 
-  ruby_version_is "2.6" do
-    describe "with an endless range" do
-      describe "and Integer values" do
-        it "yield Integer values incremented by 1 when not passed a step" do
-          eval("(-2..)").step { |x| break if x > 2; ScratchPad << x }
-          ScratchPad.recorded.should eql([-2, -1, 0, 1, 2])
-
-          ScratchPad.record []
-          eval("(-2...)").step { |x| break if x > 2; ScratchPad << x }
-          ScratchPad.recorded.should eql([-2, -1, 0, 1, 2])
-        end
+  describe "with an endless range" do
+    describe "and Integer values" do
+      it "yield Integer values incremented by 1 when not passed a step" do
+        eval("(-2..)").step { |x| break if x > 2; ScratchPad << x }
+        ScratchPad.recorded.should eql([-2, -1, 0, 1, 2])
 
-        it "yields Integer values incremented by an Integer step" do
-          eval("(-5..)").step(2) { |x| break if x > 3; ScratchPad << x }
-          ScratchPad.recorded.should eql([-5, -3, -1, 1, 3])
+        ScratchPad.record []
+        eval("(-2...)").step { |x| break if x > 2; ScratchPad << x }
+        ScratchPad.recorded.should eql([-2, -1, 0, 1, 2])
+      end
 
-          ScratchPad.record []
-          eval("(-5...)").step(2) { |x| break if x > 3; ScratchPad << x }
-          ScratchPad.recorded.should eql([-5, -3, -1, 1, 3])
-        end
+      it "yields Integer values incremented by an Integer step" do
+        eval("(-5..)").step(2) { |x| break if x > 3; ScratchPad << x }
+        ScratchPad.recorded.should eql([-5, -3, -1, 1, 3])
 
-        it "yields Float values incremented by a Float step" do
-          eval("(-2..)").step(1.5) { |x| break if x > 1.0; ScratchPad << x }
-          ScratchPad.recorded.should eql([-2.0, -0.5, 1.0])
+        ScratchPad.record []
+        eval("(-5...)").step(2) { |x| break if x > 3; ScratchPad << x }
+        ScratchPad.recorded.should eql([-5, -3, -1, 1, 3])
+      end
 
-          ScratchPad.record []
-          eval("(-2..)").step(1.5) { |x| break if x > 1.0; ScratchPad << x }
-          ScratchPad.recorded.should eql([-2.0, -0.5, 1.0])
-        end
+      it "yields Float values incremented by a Float step" do
+        eval("(-2..)").step(1.5) { |x| break if x > 1.0; ScratchPad << x }
+        ScratchPad.recorded.should eql([-2.0, -0.5, 1.0])
+
+        ScratchPad.record []
+        eval("(-2..)").step(1.5) { |x| break if x > 1.0; ScratchPad << x }
+        ScratchPad.recorded.should eql([-2.0, -0.5, 1.0])
       end
+    end
 
-      describe "and Float values" do
-        it "yields Float values incremented by 1 and less than end when not passed a step" do
-          eval("(-2.0..)").step { |x| break if x > 1.5; ScratchPad << x }
-          ScratchPad.recorded.should eql([-2.0, -1.0, 0.0, 1.0])
+    describe "and Float values" do
+      it "yields Float values incremented by 1 and less than end when not passed a step" do
+        eval("(-2.0..)").step { |x| break if x > 1.5; ScratchPad << x }
+        ScratchPad.recorded.should eql([-2.0, -1.0, 0.0, 1.0])
 
-          ScratchPad.record []
-          eval("(-2.0...)").step { |x| break if x > 1.5; ScratchPad << x }
-          ScratchPad.recorded.should eql([-2.0, -1.0, 0.0, 1.0])
-        end
+        ScratchPad.record []
+        eval("(-2.0...)").step { |x| break if x > 1.5; ScratchPad << x }
+        ScratchPad.recorded.should eql([-2.0, -1.0, 0.0, 1.0])
+      end
 
-        it "yields Float values incremented by an Integer step" do
-          eval("(-5.0..)").step(2) { |x| break if x > 3.5; ScratchPad << x }
-          ScratchPad.recorded.should eql([-5.0, -3.0, -1.0, 1.0, 3.0])
+      it "yields Float values incremented by an Integer step" do
+        eval("(-5.0..)").step(2) { |x| break if x > 3.5; ScratchPad << x }
+        ScratchPad.recorded.should eql([-5.0, -3.0, -1.0, 1.0, 3.0])
 
-          ScratchPad.record []
-          eval("(-5.0...)").step(2) { |x| break if x > 3.5; ScratchPad << x }
-          ScratchPad.recorded.should eql([-5.0, -3.0, -1.0, 1.0, 3.0])
-        end
+        ScratchPad.record []
+        eval("(-5.0...)").step(2) { |x| break if x > 3.5; ScratchPad << x }
+        ScratchPad.recorded.should eql([-5.0, -3.0, -1.0, 1.0, 3.0])
+      end
 
-        it "yields Float values incremented by a Float step" do
-          eval("(-1.0..)").step(0.5) { |x| break if x > 0.6; ScratchPad << x }
-          ScratchPad.recorded.should eql([-1.0, -0.5, 0.0, 0.5])
+      it "yields Float values incremented by a Float step" do
+        eval("(-1.0..)").step(0.5) { |x| break if x > 0.6; ScratchPad << x }
+        ScratchPad.recorded.should eql([-1.0, -0.5, 0.0, 0.5])
 
-          ScratchPad.record []
-          eval("(-1.0...)").step(0.5) { |x| break if x > 0.6; ScratchPad << x }
-          ScratchPad.recorded.should eql([-1.0, -0.5, 0.0, 0.5])
-        end
+        ScratchPad.record []
+        eval("(-1.0...)").step(0.5) { |x| break if x > 0.6; ScratchPad << x }
+        ScratchPad.recorded.should eql([-1.0, -0.5, 0.0, 0.5])
+      end
 
-        it "handles infinite values at the start" do
-          eval("(-Float::INFINITY..)").step(2) { |x| ScratchPad << x; break if ScratchPad.recorded.size == 3 }
-          ScratchPad.recorded.should eql([-Float::INFINITY, -Float::INFINITY, -Float::INFINITY])
+      it "handles infinite values at the start" do
+        eval("(-Float::INFINITY..)").step(2) { |x| ScratchPad << x; break if ScratchPad.recorded.size == 3 }
+        ScratchPad.recorded.should eql([-Float::INFINITY, -Float::INFINITY, -Float::INFINITY])
 
-          ScratchPad.record []
-          eval("(-Float::INFINITY...)").step(2) { |x| ScratchPad << x; break if ScratchPad.recorded.size == 3 }
-          ScratchPad.recorded.should eql([-Float::INFINITY, -Float::INFINITY, -Float::INFINITY])
-        end
+        ScratchPad.record []
+        eval("(-Float::INFINITY...)").step(2) { |x| ScratchPad << x; break if ScratchPad.recorded.size == 3 }
+        ScratchPad.recorded.should eql([-Float::INFINITY, -Float::INFINITY, -Float::INFINITY])
       end
+    end
 
-      describe "and String values" do
-        it "yields String values incremented by #succ and less than or equal to end when not passed a step" do
-          eval("('A'..)").step { |x| break if x > "D"; ScratchPad << x }
-          ScratchPad.recorded.should == ["A", "B", "C", "D"]
+    describe "and String values" do
+      it "yields String values incremented by #succ and less than or equal to end when not passed a step" do
+        eval("('A'..)").step { |x| break if x > "D"; ScratchPad << x }
+        ScratchPad.recorded.should == ["A", "B", "C", "D"]
 
-          ScratchPad.record []
-          eval("('A'...)").step { |x| break if x > "D"; ScratchPad << x }
-          ScratchPad.recorded.should == ["A", "B", "C", "D"]
-        end
+        ScratchPad.record []
+        eval("('A'...)").step { |x| break if x > "D"; ScratchPad << x }
+        ScratchPad.recorded.should == ["A", "B", "C", "D"]
+      end
 
-        it "yields String values incremented by #succ called Integer step times" do
-          eval("('A'..)").step(2) { |x| break if x > "F"; ScratchPad << x }
-          ScratchPad.recorded.should == ["A", "C", "E"]
+      it "yields String values incremented by #succ called Integer step times" do
+        eval("('A'..)").step(2) { |x| break if x > "F"; ScratchPad << x }
+        ScratchPad.recorded.should == ["A", "C", "E"]
 
-          ScratchPad.record []
-          eval("('A'...)").step(2) { |x| break if x > "F"; ScratchPad << x }
-          ScratchPad.recorded.should == ["A", "C", "E"]
-        end
+        ScratchPad.record []
+        eval("('A'...)").step(2) { |x| break if x > "F"; ScratchPad << x }
+        ScratchPad.recorded.should == ["A", "C", "E"]
+      end
 
-        it "raises a TypeError when passed a Float step" do
-          -> { eval("('A'..)").step(2.0) { } }.should raise_error(TypeError)
-          -> { eval("('A'...)").step(2.0) { } }.should raise_error(TypeError)
-        end
+      it "raises a TypeError when passed a Float step" do
+        -> { eval("('A'..)").step(2.0) { } }.should raise_error(TypeError)
+        -> { eval("('A'...)").step(2.0) { } }.should raise_error(TypeError)
       end
     end
   end
@@ -416,24 +414,7 @@ describe "Range#step" do
           end
         end
 
-        ruby_version_is ""..."2.6" do
-          it "raises an ArgumentError if step is 0" do
-            enum = (-1..1).step(0)
-            -> { enum.size }.should raise_error(ArgumentError)
-          end
-
-          it "raises an ArgumentError if step is 0.0" do
-            enum = (-1..1).step(0.0)
-            -> { enum.size }.should raise_error(ArgumentError)
-          end
-
-          it "raises an ArgumentError if step is negative" do
-            enum = (-1..1).step(-2)
-            -> {  enum.size }.should raise_error(ArgumentError)
-          end
-        end
-
-        ruby_version_is "2.6"..."3.0" do
+        ruby_version_is ""..."3.0" do
           it "returns Float::INFINITY for zero step" do
             (-1..1).step(0).size.should == Float::INFINITY
             (-1..1).step(0.0).size.should == Float::INFINITY
@@ -453,11 +434,9 @@ describe "Range#step" do
           (-5...5).step(2).size.should == 5
         end
 
-        ruby_version_is "2.6" do
-          it "returns the ceil of range size divided by the number of steps even if step is negative" do
-            (-1..1).step(-1).size.should == 0
-            (1..-1).step(-1).size.should == 3
-          end
+        it "returns the ceil of range size divided by the number of steps even if step is negative" do
+          (-1..1).step(-1).size.should == 0
+          (1..-1).step(-1).size.should == 3
         end
 
         it "returns the correct number of steps when one of the arguments is a float" do
@@ -496,23 +475,15 @@ describe "Range#step" do
       end
 
       describe "type" do
-        ruby_version_is ""..."2.6" do
-          it "returns an instance of Enumerator" do
-            (1..10).step.class.should == Enumerator
+        context "when both begin and end are numerics" do
+          it "returns an instance of Enumerator::ArithmeticSequence" do
+            (1..10).step.class.should == Enumerator::ArithmeticSequence
           end
         end
 
-        ruby_version_is "2.6" do
-          context "when both begin and end are numerics" do
-            it "returns an instance of Enumerator::ArithmeticSequence" do
-              (1..10).step.class.should == Enumerator::ArithmeticSequence
-            end
-          end
-
-          context "when begin and end are not numerics" do
-            it "returns an instance of Enumerator" do
-              ("a".."z").step.class.should == Enumerator
-            end
+        context "when begin and end are not numerics" do
+          it "returns an instance of Enumerator" do
+            ("a".."z").step.class.should == Enumerator
           end
         end
       end
diff --git a/spec/ruby/core/range/to_a_spec.rb b/spec/ruby/core/range/to_a_spec.rb
index 9a1352b7b0..52ebc02941 100644
--- a/spec/ruby/core/range/to_a_spec.rb
+++ b/spec/ruby/core/range/to_a_spec.rb
@@ -29,10 +29,8 @@ describe "Range#to_a" do
     ('Σ'..'Ω').to_a.should == ["Σ", "Τ", "Υ", "Φ", "Χ", "Ψ", "Ω"]
   end
 
-  ruby_version_is "2.6" do
-    it "throws an exception for endless ranges" do
-      -> { eval("(1..)").to_a }.should raise_error(RangeError)
-    end
+  it "throws an exception for endless ranges" do
+    -> { eval("(1..)").to_a }.should raise_error(RangeError)
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/range/to_s_spec.rb b/spec/ruby/core/range/to_s_spec.rb
index 59672da822..581c2e7d90 100644
--- a/spec/ruby/core/range/to_s_spec.rb
+++ b/spec/ruby/core/range/to_s_spec.rb
@@ -11,11 +11,9 @@ describe "Range#to_s" do
     (0.5..2.4).to_s.should == "0.5..2.4"
   end
 
-  ruby_version_is "2.6" do
-    it "can show endless ranges" do
-      eval("(1..)").to_s.should == "1.."
-      eval("(1.0...)").to_s.should == "1.0..."
-    end
+  it "can show endless ranges" do
+    eval("(1..)").to_s.should == "1.."
+    eval("(1.0...)").to_s.should == "1.0..."
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/string/gsub_spec.rb b/spec/ruby/core/string/gsub_spec.rb
index 6789199ff3..ad41b7e0a2 100644
--- a/spec/ruby/core/string/gsub_spec.rb
+++ b/spec/ruby/core/string/gsub_spec.rb
@@ -594,6 +594,14 @@ describe "String#gsub with pattern and without replacement and block" do
   end
 end
 
+describe "String#gsub with a string pattern" do
+  it "handles multibyte characters" do
+    "é".gsub("é", "â").should == "â"
+    "aé".gsub("é", "â").should == "aâ"
+    "éa".gsub("é", "â").should == "âa"
+  end
+end
+
 describe "String#gsub! with pattern and replacement" do
   it "modifies self in place and returns self" do
     a = "hello"
diff --git a/spec/ruby/core/string/index_spec.rb b/spec/ruby/core/string/index_spec.rb
index 8d2c8af193..5d77a88e4e 100644
--- a/spec/ruby/core/string/index_spec.rb
+++ b/spec/ruby/core/string/index_spec.rb
@@ -146,6 +146,7 @@ describe "String#index with String" do
 
   it "returns the character index after offset" do
     "われわれ".index("わ", 1).should == 2
+    "ありがとうありがとう".index("が", 3).should == 7
   end
 
   it "returns the character index after a partial first match" do
diff --git a/spec/ruby/core/string/scrub_spec.rb b/spec/ruby/core/string/scrub_spec.rb
index b513acfb70..5c67ad01bc 100644
--- a/spec/ruby/core/string/scrub_spec.rb
+++ b/spec/ruby/core/string/scrub_spec.rb
@@ -119,4 +119,10 @@ describe "String#scrub!" do
     input.scrub!
     input.instance_variable_get(:@a).should == 'b'
   end
+
+  it "accepts a frozen string as a replacement" do
+    input = "a\xE2"
+    input.scrub!('.'.freeze)
+    input.should == 'a.'
+  end
 end
diff --git a/spec/ruby/core/string/shared/slice.rb b/spec/ruby/core/string/shared/slice.rb
index a674e0b6ef..1db8fd6730 100644
--- a/spec/ruby/core/string/shared/slice.rb
+++ b/spec/ruby/core/string/shared/slice.rb
@@ -327,13 +327,11 @@ describe :string_slice_range, shared: true do
     -> { "hello".send(@method, 0..bignum_value) }.should raise_error(RangeError)
   end
 
-  ruby_version_is "2.6" do
-    it "works with endless ranges" do
-      "hello there".send(@method, eval("(2..)")).should == "llo there"
-      "hello there".send(@method, eval("(2...)")).should == "llo there"
-      "hello there".send(@method, eval("(-4..)")).should == "here"
-      "hello there".send(@method, eval("(-4...)")).should == "here"
-    end
+  it "works with endless ranges" do
+    "hello there".send(@method, eval("(2..)")).should == "llo there"
+    "hello there".send(@method, eval("(2...)")).should == "llo there"
+    "hello there".send(@method, eval("(-4..)")).should == "here"
+    "hello there".send(@method, eval("(-4...)")).should == "here"
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/string/split_spec.rb b/spec/ruby/core/string/split_spec.rb
index e3641b33e0..a373be360d 100644
--- a/spec/ruby/core/string/split_spec.rb
+++ b/spec/ruby/core/string/split_spec.rb
@@ -471,108 +471,106 @@ describe "String#split with Regexp" do
     results.should == [%w[a b c d e]] * 10
   end
 
-  ruby_version_is "2.6" do
-    context "when a block is given" do
-      it "yields each split substring with default pattern" do
-        a = []
-        returned_object = "chunky bacon".split { |str| a << str.capitalize }
+  context "when a block is given" do
+    it "yields each split substring with default pattern" do
+      a = []
+      returned_object = "chunky bacon".split { |str| a << str.capitalize }
 
-        returned_object.should == "chunky bacon"
-        a.should == ["Chunky", "Bacon"]
-      end
+      returned_object.should == "chunky bacon"
+      a.should == ["Chunky", "Bacon"]
+    end
 
-      it "yields each split substring with default pattern for a non-ASCII string" do
-        a = []
-        returned_object = "l'été arrive bientôt".split { |str| a << str }
+    it "yields each split substring with default pattern for a non-ASCII string" do
+      a = []
+      returned_object = "l'été arrive bientôt".split { |str| a << str }
 
-        returned_object.should == "l'été arrive bientôt"
-        a.should == ["l'été", "arrive", "bientôt"]
-      end
+      returned_object.should == "l'été arrive bientôt"
+      a.should == ["l'été", "arrive", "bientôt"]
+    end
 
-      it "yields the string when limit is 1" do
-        a = []
-        returned_object = "chunky bacon".split("", 1) { |str| a << str.capitalize }
+    it "yields the string when limit is 1" do
+      a = []
+      returned_object = "chunky bacon".split("", 1) { |str| a << str.capitalize }
 
-        returned_object.should == "chunky bacon"
-        a.should == ["Chunky bacon"]
-      end
+      returned_object.should == "chunky bacon"
+      a.should == ["Chunky bacon"]
+    end
 
-      it "yields each split letter" do
-        a = []
-        returned_object = "chunky".split("", 0) { |str| a << str.capitalize }
+    it "yields each split letter" do
+      a = []
+      returned_object = "chunky".split("", 0) { |str| a << str.capitalize }
 
-        returned_object.should == "chunky"
-        a.should == %w(C H U N K Y)
-      end
+      returned_object.should == "chunky"
+      a.should == %w(C H U N K Y)
+    end
 
-      it "yields each split substring with a pattern" do
-        a = []
-        returned_object = "chunky-bacon".split("-", 0) { |str| a << str.capitalize }
+    it "yields each split substring with a pattern" do
+      a = []
+      returned_object = "chunky-bacon".split("-", 0) { |str| a << str.capitalize }
 
-        returned_object.should == "chunky-bacon"
-        a.should == ["Chunky", "Bacon"]
-      end
+      returned_object.should == "chunky-bacon"
+      a.should == ["Chunky", "Bacon"]
+    end
 
-      it "yields each split substring with empty regexp pattern" do
-        a = []
-        returned_object = "chunky".split(//) { |str| a << str.capitalize }
+    it "yields each split substring with empty regexp pattern" do
+      a = []
+      returned_object = "chunky".split(//) { |str| a << str.capitalize }
 
-        returned_object.should == "chunky"
-        a.should == %w(C H U N K Y)
-      end
+      returned_object.should == "chunky"
+      a.should == %w(C H U N K Y)
+    end
 
-      it "yields each split substring with empty regexp pattern and limit" do
-        a = []
-        returned_object = "chunky".split(//, 3) { |str| a << str.capitalize }
+    it "yields each split substring with empty regexp pattern and limit" do
+      a = []
+      returned_object = "chunky".split(//, 3) { |str| a << str.capitalize }
 
-        returned_object.should == "chunky"
-        a.should == %w(C H Unky)
-      end
+      returned_object.should == "chunky"
+      a.should == %w(C H Unky)
+    end
 
-      it "yields each split substring with a regexp pattern" do
-        a = []
-        returned_object = "chunky:bacon".split(/:/) { |str| a << str.capitalize }
+    it "yields each split substring with a regexp pattern" do
+      a = []
+      returned_object = "chunky:bacon".split(/:/) { |str| a << str.capitalize }
 
-        returned_object.should == "chunky:bacon"
-        a.should == ["Chunky", "Bacon"]
-      end
+      returned_object.should == "chunky:bacon"
+      a.should == ["Chunky", "Bacon"]
+    end
 
-      it "returns a string as is (and doesn't call block) if it is empty" do
-        a = []
-        returned_object = "".split { |str| a << str.capitalize }
+    it "returns a string as is (and doesn't call block) if it is empty" do
+      a = []
+      returned_object = "".split { |str| a << str.capitalize }
 
-        returned_object.should == ""
-        a.should == []
-      end
+      returned_object.should == ""
+      a.should == []
     end
+  end
 
-    describe "for a String subclass" do
-      ruby_version_is ''...'3.0' do
-        it "yields instances of the same subclass" do
-          a = []
-          StringSpecs::MyString.new("a|b").split("|") { |str| a << str }
-          first, last = a
+  describe "for a String subclass" do
+    ruby_version_is ''...'3.0' do
+      it "yields instances of the same subclass" do
+        a = []
+        StringSpecs::MyString.new("a|b").split("|") { |str| a << str }
+        first, last = a
 
-          first.should be_an_instance_of(StringSpecs::MyString)
-          first.should == "a"
+        first.should be_an_instance_of(StringSpecs::MyString)
+        first.should == "a"
 
-          last.should be_an_instance_of(StringSpecs::MyString)
-          last.should == "b"
-        end
+        last.should be_an_instance_of(StringSpecs::MyString)
+        last.should == "b"
       end
+    end
 
-      ruby_version_is '3.0' do
-        it "yields instances of String" do
-          a = []
-          StringSpecs::MyString.new("a|b").split("|") { |str| a << str }
-          first, last = a
+    ruby_version_is '3.0' do
+      it "yields instances of String" do
+        a = []
+        StringSpecs::MyString.new("a|b").split("|") { |str| a << str }
+        first, last = a
 
-          first.should be_an_instance_of(String)
-          first.should == "a"
+        first.should be_an_instance_of(String)
+        first.should == "a"
 
-          last.should be_an_instance_of(String)
-          last.should == "b"
-        end
+        last.should be_an_instance_of(String)
+        last.should == "b"
       end
     end
   end
diff --git a/spec/ruby/core/string/uminus_spec.rb b/spec/ruby/core/string/uminus_spec.rb
index 3a81b64126..800dca5044 100644
--- a/spec/ruby/core/string/uminus_spec.rb
+++ b/spec/ruby/core/string/uminus_spec.rb
@@ -31,43 +31,13 @@ describe 'String#-@' do
     (-"unfrozen string").should_not equal(-"another unfrozen string")
   end
 
-  ruby_version_is ""..."2.6" do
-    it "does not deduplicate already frozen strings" do
-      dynamic = %w(this string is frozen).join(' ').freeze
+  it "deduplicates frozen strings" do
+    dynamic = %w(this string is frozen).join(' ').freeze
 
-      dynamic.should_not equal("this string is frozen".freeze)
+    dynamic.should_not equal("this string is frozen".freeze)
 
-      (-dynamic).should_not equal("this string is frozen".freeze)
-      (-dynamic).should_not equal(-"this string is frozen".freeze)
-      (-dynamic).should == "this string is frozen"
-    end
-
-    it "does not deduplicate tainted strings" do
-      dynamic = %w(this string is frozen).join(' ')
-      dynamic.taint
-      (-dynamic).should_not equal("this string is frozen".freeze)
-      (-dynamic).should_not equal(-"this string is frozen".freeze)
-      (-dynamic).should == "this string is frozen"
-    end
-
-    it "does not deduplicate strings with additional instance variables" do
-      dynamic = %w(this string is frozen).join(' ')
-      dynamic.instance_variable_set(:@foo, :bar)
-      (-dynamic).should_not equal("this string is frozen".freeze)
-      (-dynamic).should_not equal(-"this string is frozen".freeze)
-      (-dynamic).should == "this string is frozen"
-    end
-  end
-
-  ruby_version_is "2.6" do
-    it "deduplicates frozen strings" do
-      dynamic = %w(this string is frozen).join(' ').freeze
-
-      dynamic.should_not equal("this string is frozen".freeze)
-
-      (-dynamic).should equal("this string is frozen".freeze)
-      (-dynamic).should equal(-"this string is frozen".freeze)
-    end
+    (-dynamic).should equal("this string is frozen".freeze)
+    (-dynamic).should equal(-"this string is frozen".freeze)
   end
 
   ruby_version_is "3.0" do
diff --git a/spec/ruby/core/struct/filter_spec.rb b/spec/ruby/core/struct/filter_spec.rb
index 1105ed064a..0ccd8ad6b2 100644
--- a/spec/ruby/core/struct/filter_spec.rb
+++ b/spec/ruby/core/struct/filter_spec.rb
@@ -3,10 +3,8 @@ require_relative 'shared/select'
 require_relative 'shared/accessor'
 require_relative '../enumerable/shared/enumeratorized'
 
-ruby_version_is "2.6" do
-  describe "Struct#filter" do
-    it_behaves_like :struct_select, :filter
-    it_behaves_like :struct_accessor, :filter
-    it_behaves_like :enumeratorized_with_origin_size, :filter, Struct.new(:foo).new
-  end
+describe "Struct#filter" do
+  it_behaves_like :struct_select, :filter
+  it_behaves_like :struct_accessor, :filter
+  it_behaves_like :enumeratorized_with_origin_size, :filter, Struct.new(:foo).new
 end
diff --git a/spec/ruby/core/struct/to_h_spec.rb b/spec/ruby/core/struct/to_h_spec.rb
index b5f4e40701..bfb0af07ba 100644
--- a/spec/ruby/core/struct/to_h_spec.rb
+++ b/spec/ruby/core/struct/to_h_spec.rb
@@ -13,46 +13,44 @@ describe "Struct#to_h" do
     car.make.should == 'Ford'
   end
 
-  ruby_version_is "2.6" do
-    context "with block" do
-      it "converts [key, value] pairs returned by the block to a hash" do
-        car = StructClasses::Car.new('Ford', 'Ranger')
-
-        h = car.to_h { |k, v| [k.to_s, "#{v}".downcase] }
-        h.should == { "make" => "ford", "model" => "ranger", "year" => "" }
-      end
-
-      it "raises ArgumentError if block returns longer or shorter array" do
-        -> do
-          StructClasses::Car.new.to_h { |k, v| [k.to_s, "#{v}".downcase, 1] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-
-        -> do
-          StructClasses::Car.new.to_h { |k, v| [k] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-      end
-
-      it "raises TypeError if block returns something other than Array" do
-        -> do
-          StructClasses::Car.new.to_h { |k, v| "not-array" }
-        end.should raise_error(TypeError, /wrong element type String/)
-      end
-
-      it "coerces returned pair to Array with #to_ary" do
-        x = mock('x')
-        x.stub!(:to_ary).and_return([:b, 'b'])
-
-        StructClasses::Car.new.to_h { |k| x }.should == { :b => 'b' }
-      end
-
-      it "does not coerce returned pair to Array with #to_a" do
-        x = mock('x')
-        x.stub!(:to_a).and_return([:b, 'b'])
-
-        -> do
-          StructClasses::Car.new.to_h { |k| x }
-        end.should raise_error(TypeError, /wrong element type MockObject/)
-      end
+  context "with block" do
+    it "converts [key, value] pairs returned by the block to a hash" do
+      car = StructClasses::Car.new('Ford', 'Ranger')
+
+      h = car.to_h { |k, v| [k.to_s, "#{v}".downcase] }
+      h.should == { "make" => "ford", "model" => "ranger", "year" => "" }
+    end
+
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        StructClasses::Car.new.to_h { |k, v| [k.to_s, "#{v}".downcase, 1] }
+      end.should raise_error(ArgumentError, /element has wrong array length/)
+
+      -> do
+        StructClasses::Car.new.to_h { |k, v| [k] }
+      end.should raise_error(ArgumentError, /element has wrong array length/)
+    end
+
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        StructClasses::Car.new.to_h { |k, v| "not-array" }
+      end.should raise_error(TypeError, /wrong element type String/)
+    end
+
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
+
+      StructClasses::Car.new.to_h { |k| x }.should == { :b => 'b' }
+    end
+
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
+
+      -> do
+        StructClasses::Car.new.to_h { |k| x }
+      end.should raise_error(TypeError, /wrong element type MockObject/)
     end
   end
 end
diff --git a/spec/ruby/core/thread/backtrace_locations_spec.rb b/spec/ruby/core/thread/backtrace_locations_spec.rb
index 1f77e13378..237941c214 100644
--- a/spec/ruby/core/thread/backtrace_locations_spec.rb
+++ b/spec/ruby/core/thread/backtrace_locations_spec.rb
@@ -43,12 +43,10 @@ describe "Thread#backtrace_locations" do
     Thread.current.backtrace_locations(2..-2).map(&:to_s).should == Thread.current.backtrace_locations[2..-2].map(&:to_s)
   end
 
-  ruby_version_is "2.6" do
-    it "can be called with an endless range" do
-      locations1 = Thread.current.backtrace_locations(0)
-      locations2 = Thread.current.backtrace_locations(eval("(2..)"))
-      locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
-    end
+  it "can be called with an endless range" do
+    locations1 = Thread.current.backtrace_locations(0)
+    locations2 = Thread.current.backtrace_locations(eval("(2..)"))
+    locations2.map(&:to_s).should == locations1[2..-1].map(&:to_s)
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/core/thread/shared/wakeup.rb b/spec/ruby/core/thread/shared/wakeup.rb
index f111edf0fd..6f010fea25 100644
--- a/spec/ruby/core/thread/shared/wakeup.rb
+++ b/spec/ruby/core/thread/shared/wakeup.rb
@@ -36,7 +36,7 @@ describe :thread_wakeup, shared: true do
 
   it "does not result in a deadlock" do
     t = Thread.new do
-      100.times { Thread.stop }
+      10.times { Thread.stop }
     end
 
     while t.status
@@ -47,6 +47,7 @@ describe :thread_wakeup, shared: true do
         t.status.should == false
       end
       Thread.pass
+      sleep 0.001
     end
 
     t.status.should == false
diff --git a/spec/ruby/core/time/at_spec.rb b/spec/ruby/core/time/at_spec.rb
index ff43537dcc..2cc46ab8c9 100644
--- a/spec/ruby/core/time/at_spec.rb
+++ b/spec/ruby/core/time/at_spec.rb
@@ -218,55 +218,53 @@ describe "Time.at" do
     end
   end
 
-  ruby_version_is "2.6" do
-    describe ":in keyword argument" do
-      before do
-        @epoch_time = Time.now.to_i
-      end
+  describe ":in keyword argument" do
+    before do
+      @epoch_time = Time.now.to_i
+    end
 
-      it "could be UTC offset as a String in '+HH:MM or '-HH:MM' format" do
-        time = Time.at(@epoch_time, in: "+05:00")
+    it "could be UTC offset as a String in '+HH:MM or '-HH:MM' format" do
+      time = Time.at(@epoch_time, in: "+05:00")
 
-        time.utc_offset.should == 5*60*60
-        time.zone.should == nil
-        time.to_i.should == @epoch_time
+      time.utc_offset.should == 5*60*60
+      time.zone.should == nil
+      time.to_i.should == @epoch_time
 
-        time = Time.at(@epoch_time, in: "-09:00")
+      time = Time.at(@epoch_time, in: "-09:00")
 
-        time.utc_offset.should == -9*60*60
-        time.zone.should == nil
-        time.to_i.should == @epoch_time
-      end
+      time.utc_offset.should == -9*60*60
+      time.zone.should == nil
+      time.to_i.should == @epoch_time
+    end
 
-      it "could be UTC offset as a number of seconds" do
-        time = Time.at(@epoch_time, in: 5*60*60)
+    it "could be UTC offset as a number of seconds" do
+      time = Time.at(@epoch_time, in: 5*60*60)
 
-        time.utc_offset.should == 5*60*60
-        time.zone.should == nil
-        time.to_i.should == @epoch_time
+      time.utc_offset.should == 5*60*60
+      time.zone.should == nil
+      time.to_i.should == @epoch_time
 
-        time = Time.at(@epoch_time, in: -9*60*60)
+      time = Time.at(@epoch_time, in: -9*60*60)
 
-        time.utc_offset.should == -9*60*60
-        time.zone.should == nil
-        time.to_i.should == @epoch_time
-      end
+      time.utc_offset.should == -9*60*60
+      time.zone.should == nil
+      time.to_i.should == @epoch_time
+    end
 
-      it "could be a timezone object" do
-        zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
-        time = Time.at(@epoch_time, in: zone)
+    it "could be a timezone object" do
+      zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
+      time = Time.at(@epoch_time, in: zone)
 
-        time.utc_offset.should == 5*3600+30*60
-        time.zone.should == zone
-        time.to_i.should == @epoch_time
+      time.utc_offset.should == 5*3600+30*60
+      time.zone.should == zone
+      time.to_i.should == @epoch_time
 
-        zone = TimeSpecs::TimezoneWithName.new(name: "PST")
-        time = Time.at(@epoch_time, in: zone)
+      zone = TimeSpecs::TimezoneWithName.new(name: "PST")
+      time = Time.at(@epoch_time, in: zone)
 
-        time.utc_offset.should == -9*60*60
-        time.zone.should == zone
-        time.to_i.should == @epoch_time
-      end
+      time.utc_offset.should == -9*60*60
+      time.zone.should == zone
+      time.to_i.should == @epoch_time
     end
   end
 end
diff --git a/spec/ruby/core/time/getlocal_spec.rb b/spec/ruby/core/time/getlocal_spec.rb
index 7196577dab..926a6dbf45 100644
--- a/spec/ruby/core/time/getlocal_spec.rb
+++ b/spec/ruby/core/time/getlocal_spec.rb
@@ -97,71 +97,69 @@ describe "Time#getlocal" do
     -> { t.getlocal(86400) }.should raise_error(ArgumentError)
   end
 
-  ruby_version_is "2.6" do
-    describe "with a timezone argument" do
-      it "returns a Time in the timezone" do
-        zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
-        time = Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone)
-
-        time.zone.should == zone
-        time.utc_offset.should == 5*3600+30*60
-      end
+  describe "with a timezone argument" do
+    it "returns a Time in the timezone" do
+      zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
+      time = Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone)
 
-      it "accepts timezone argument that must have #local_to_utc and #utc_to_local methods" do
-        zone = Object.new
-        def zone.utc_to_local(time)
-          time
-        end
-        def zone.local_to_utc(time)
-          time
-        end
+      time.zone.should == zone
+      time.utc_offset.should == 5*3600+30*60
+    end
 
-        -> {
-          Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone).should be_kind_of(Time)
-        }.should_not raise_error
+    it "accepts timezone argument that must have #local_to_utc and #utc_to_local methods" do
+      zone = Object.new
+      def zone.utc_to_local(time)
+        time
+      end
+      def zone.local_to_utc(time)
+        time
       end
 
-      it "raises TypeError if timezone does not implement #utc_to_local method" do
-        zone = Object.new
-        def zone.local_to_utc(time)
-          time
-        end
+      -> {
+        Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone).should be_kind_of(Time)
+      }.should_not raise_error
+    end
 
-        -> {
-          Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone)
-        }.should raise_error(TypeError, /can't convert \w+ into an exact number/)
+    it "raises TypeError if timezone does not implement #utc_to_local method" do
+      zone = Object.new
+      def zone.local_to_utc(time)
+        time
       end
 
-      it "does not raise exception if timezone does not implement #local_to_utc method" do
-        zone = Object.new
-        def zone.utc_to_local(time)
-          time
-        end
+      -> {
+        Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone)
+      }.should raise_error(TypeError, /can't convert \w+ into an exact number/)
+    end
 
-        -> {
-          Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone).should be_kind_of(Time)
-        }.should_not raise_error
+    it "does not raise exception if timezone does not implement #local_to_utc method" do
+      zone = Object.new
+      def zone.utc_to_local(time)
+        time
       end
 
-      context "subject's class implements .find_timezone method" do
-        it "calls .find_timezone to build a time object if passed zone name as a timezone argument" do
-          time = TimeSpecs::TimeWithFindTimezone.utc(2000, 1, 1, 12, 0, 0).getlocal("Asia/Colombo")
-          time.zone.should be_kind_of TimeSpecs::TimezoneWithName
-          time.zone.name.should == "Asia/Colombo"
+      -> {
+        Time.utc(2000, 1, 1, 12, 0, 0).getlocal(zone).should be_kind_of(Time)
+      }.should_not raise_error
+    end
+
+    context "subject's class implements .find_timezone method" do
+      it "calls .find_timezone to build a time object if passed zone name as a timezone argument" do
+        time = TimeSpecs::TimeWithFindTimezone.utc(2000, 1, 1, 12, 0, 0).getlocal("Asia/Colombo")
+        time.zone.should be_kind_of TimeSpecs::TimezoneWithName
+        time.zone.name.should == "Asia/Colombo"
 
-          time = TimeSpecs::TimeWithFindTimezone.utc(2000, 1, 1, 12, 0, 0).getlocal("some invalid zone name")
-          time.zone.should be_kind_of TimeSpecs::TimezoneWithName
-          time.zone.name.should == "some invalid zone name"
-        end
+        time = TimeSpecs::TimeWithFindTimezone.utc(2000, 1, 1, 12, 0, 0).getlocal("some invalid zone name")
+        time.zone.should be_kind_of TimeSpecs::TimezoneWithName
+        time.zone.name.should == "some invalid zone name"
+      end
 
-        it "does not call .find_timezone if passed any not string/numeric/timezone timezone argument" do
-          [Object.new, [], {}, :"some zone"].each do |zone|
-            time = TimeSpecs::TimeWithFindTimezone.utc(2000, 1, 1, 12, 0, 0)
+      it "does not call .find_timezone if passed any not string/numeric/timezone timezone argument" do
+        [Object.new, [], {}, :"some zone"].each do |zone|
+          time = TimeSpecs::TimeWithFindTimezone.utc(2000, 1, 1, 12, 0, 0)
 
-            -> {
-              time.getlocal(zone)
-            }.should raise_error(TypeError, /can't convert \w+ into an exact number/)
-          end
+          -> {
+            time.getlocal(zone)
+          }.should raise_error(TypeError, /can't convert \w+ into an exact number/)
         end
       end
     end
diff --git a/spec/ruby/core/time/minus_spec.rb b/spec/ruby/core/time/minus_spec.rb
index 995dac8462..8449778465 100644
--- a/spec/ruby/core/time/minus_spec.rb
+++ b/spec/ruby/core/time/minus_spec.rb
@@ -98,14 +98,12 @@ describe "Time#-" do
     time_with_zone.zone.should == (time_with_zone - 1).zone
   end
 
-  ruby_version_is "2.6" do
-    context "zone is a timezone object" do
-      it "preserves time zone" do
-        zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
-        time = Time.new(2012, 1, 1, 12, 0, 0, zone) - 1
-
-        time.zone.should == zone
-      end
+  context "zone is a timezone object" do
+    it "preserves time zone" do
+      zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
+      time = Time.new(2012, 1, 1, 12, 0, 0, zone) - 1
+
+      time.zone.should == zone
     end
   end
 
diff --git a/spec/ruby/core/time/new_spec.rb b/spec/ruby/core/time/new_spec.rb
index a4bb5b362c..09b4d03a44 100644
--- a/spec/ruby/core/time/new_spec.rb
+++ b/spec/ruby/core/time/new_spec.rb
@@ -121,216 +121,214 @@ describe "Time.new with a utc_offset argument" do
   end
 end
 
-ruby_version_is "2.6" do
-  describe "Time.new with a timezone argument" do
-    it "returns a Time in the timezone" do
-      zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
-      time = Time.new(2000, 1, 1, 12, 0, 0, zone)
+describe "Time.new with a timezone argument" do
+  it "returns a Time in the timezone" do
+    zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
+    time = Time.new(2000, 1, 1, 12, 0, 0, zone)
+
+    time.zone.should == zone
+    time.utc_offset.should == 5*3600+30*60
+    ruby_version_is "3.0" do
+      time.wday.should == 6
+      time.yday.should == 1
+    end
+  end
 
-      time.zone.should == zone
-      time.utc_offset.should == 5*3600+30*60
-      ruby_version_is "3.0" do
-        time.wday.should == 6
-        time.yday.should == 1
-      end
+  it "accepts timezone argument that must have #local_to_utc and #utc_to_local methods" do
+    zone = Object.new
+    def zone.utc_to_local(time)
+      time
     end
+    def zone.local_to_utc(time)
+      time
+    end
+
+    -> {
+      Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
+    }.should_not raise_error
+  end
 
-    it "accepts timezone argument that must have #local_to_utc and #utc_to_local methods" do
+  it "raises TypeError if timezone does not implement #local_to_utc method" do
+    zone = Object.new
+    def zone.utc_to_local(time)
+      time
+    end
+
+    -> {
+      Time.new(2000, 1, 1, 12, 0, 0, zone)
+    }.should raise_error(TypeError, /can't convert \w+ into an exact number/)
+  end
+
+  it "does not raise exception if timezone does not implement #utc_to_local method" do
+    zone = Object.new
+    def zone.local_to_utc(time)
+      time
+    end
+
+    -> {
+      Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
+    }.should_not raise_error
+  end
+
+  # The result also should be a Time or Time-like object (not necessary to be the same class)
+  # The zone of the result is just ignored
+  describe "returned value by #utc_to_local and #local_to_utc methods" do
+    it "could be Time instance" do
       zone = Object.new
-      def zone.utc_to_local(time)
-        time
-      end
-      def zone.local_to_utc(time)
-        time
+      def zone.local_to_utc(t)
+        Time.utc(t.year, t.mon, t.day, t.hour - 1, t.min, t.sec)
       end
 
       -> {
         Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
+        Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 60*60
       }.should_not raise_error
     end
 
-    it "raises TypeError if timezone does not implement #local_to_utc method" do
+    it "could be Time subclass instance" do
       zone = Object.new
-      def zone.utc_to_local(time)
-        time
+      def zone.local_to_utc(t)
+        Class.new(Time).utc(t.year, t.mon, t.day, t.hour - 1, t.min, t.sec)
       end
 
       -> {
-        Time.new(2000, 1, 1, 12, 0, 0, zone)
-      }.should raise_error(TypeError, /can't convert \w+ into an exact number/)
+        Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
+        Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 60*60
+      }.should_not raise_error
     end
 
-    it "does not raise exception if timezone does not implement #utc_to_local method" do
+    it "could be any object with #to_i method" do
       zone = Object.new
       def zone.local_to_utc(time)
-        time
+        Struct.new(:to_i).new(time.to_i - 60*60)
       end
 
       -> {
         Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
+        Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 60*60
       }.should_not raise_error
     end
 
-    # The result also should be a Time or Time-like object (not necessary to be the same class)
-    # The zone of the result is just ignored
-    describe "returned value by #utc_to_local and #local_to_utc methods" do
-      it "could be Time instance" do
-        zone = Object.new
-        def zone.local_to_utc(t)
-          Time.utc(t.year, t.mon, t.day, t.hour - 1, t.min, t.sec)
-        end
-
-        -> {
-          Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
-          Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 60*60
-        }.should_not raise_error
-      end
-
-      it "could be Time subclass instance" do
-        zone = Object.new
-        def zone.local_to_utc(t)
-          Class.new(Time).utc(t.year, t.mon, t.day, t.hour - 1, t.min, t.sec)
-        end
-
-        -> {
-          Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
-          Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 60*60
-        }.should_not raise_error
-      end
-
-      it "could be any object with #to_i method" do
-        zone = Object.new
-        def zone.local_to_utc(time)
-          Struct.new(:to_i).new(time.to_i - 60*60)
-        end
-
-        -> {
-          Time.new(2000, 1, 1, 12, 0, 0, zone).should be_kind_of(Time)
-          Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 60*60
-        }.should_not raise_error
-      end
-
-      it "could have any #zone and #utc_offset because they are ignored" do
-        zone = Object.new
-        def zone.local_to_utc(time)
-          Struct.new(:to_i, :zone, :utc_offset).new(time.to_i, 'America/New_York', -5*60*60)
-        end
-        Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 0
-
-        zone = Object.new
-        def zone.local_to_utc(time)
-          Struct.new(:to_i, :zone, :utc_offset).new(time.to_i, 'Asia/Tokyo', 9*60*60)
-        end
-        Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 0
+    it "could have any #zone and #utc_offset because they are ignored" do
+      zone = Object.new
+      def zone.local_to_utc(time)
+        Struct.new(:to_i, :zone, :utc_offset).new(time.to_i, 'America/New_York', -5*60*60)
       end
+      Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 0
 
-      it "leads to raising Argument error if difference between argument and result is too large" do
-        zone = Object.new
-        def zone.local_to_utc(t)
-          Time.utc(t.year, t.mon, t.day + 1, t.hour, t.min, t.sec)
-        end
-
-        -> {
-          Time.new(2000, 1, 1, 12, 0, 0, zone)
-        }.should raise_error(ArgumentError, "utc_offset out of range")
+      zone = Object.new
+      def zone.local_to_utc(time)
+        Struct.new(:to_i, :zone, :utc_offset).new(time.to_i, 'Asia/Tokyo', 9*60*60)
       end
+      Time.new(2000, 1, 1, 12, 0, 0, zone).utc_offset.should == 0
     end
 
-    # https://github.com/ruby/ruby/blob/v2_6_0/time.c#L5330
-    #
-    # Time-like argument to these methods is similar to a Time object in UTC without sub-second;
-    # it has attribute readers for the parts, e.g. year, month, and so on, and epoch time readers, to_i
-    #
-    # The sub-second attributes are fixed as 0, and utc_offset, zone, isdst, and their aliases are same as a Time object in UTC
-    describe "Time-like argument of #utc_to_local and #local_to_utc methods" do
-      before do
-        @obj = TimeSpecs::TimeLikeArgumentRecorder.result
-        @obj.should_not == nil
+    it "leads to raising Argument error if difference between argument and result is too large" do
+      zone = Object.new
+      def zone.local_to_utc(t)
+        Time.utc(t.year, t.mon, t.day + 1, t.hour, t.min, t.sec)
       end
 
-      it "implements subset of Time methods" do
-        [
-          :year, :mon, :month, :mday, :hour, :min, :sec,
-          :tv_sec, :tv_usec, :usec, :tv_nsec, :nsec, :subsec,
-          :to_i, :to_f, :to_r, :+, :-,
-          :isdst, :dst?, :zone, :gmtoff, :gmt_offset, :utc_offset, :utc?, :gmt?,
-          :to_s, :inspect, :to_a, :to_time,
-        ].each do |name|
-          @obj.respond_to?(name).should == true
-        end
-      end
+      -> {
+        Time.new(2000, 1, 1, 12, 0, 0, zone)
+      }.should raise_error(ArgumentError, "utc_offset out of range")
+    end
+  end
 
-      it "has attribute values the same as a Time object in UTC" do
-        @obj.usec.should == 0
-        @obj.nsec.should == 0
-        @obj.subsec.should == 0
-        @obj.tv_usec.should == 0
-        @obj.tv_nsec.should == 0
+  # https://github.com/ruby/ruby/blob/v2_6_0/time.c#L5330
+  #
+  # Time-like argument to these methods is similar to a Time object in UTC without sub-second;
+  # it has attribute readers for the parts, e.g. year, month, and so on, and epoch time readers, to_i
+  #
+  # The sub-second attributes are fixed as 0, and utc_offset, zone, isdst, and their aliases are same as a Time object in UTC
+  describe "Time-like argument of #utc_to_local and #local_to_utc methods" do
+    before do
+      @obj = TimeSpecs::TimeLikeArgumentRecorder.result
+      @obj.should_not == nil
+    end
 
-        @obj.utc_offset.should == 0
-        @obj.zone.should == "UTC"
-        @obj.isdst.should == Time.new.utc.isdst
+    it "implements subset of Time methods" do
+      [
+        :year, :mon, :month, :mday, :hour, :min, :sec,
+        :tv_sec, :tv_usec, :usec, :tv_nsec, :nsec, :subsec,
+        :to_i, :to_f, :to_r, :+, :-,
+        :isdst, :dst?, :zone, :gmtoff, :gmt_offset, :utc_offset, :utc?, :gmt?,
+        :to_s, :inspect, :to_a, :to_time,
+      ].each do |name|
+        @obj.respond_to?(name).should == true
       end
     end
 
-    context "#name method" do
-      it "uses the optional #name method for marshaling" do
-        zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
-        time = Time.new(2000, 1, 1, 12, 0, 0, zone)
-        time_loaded = Marshal.load(Marshal.dump(time))
+    it "has attribute values the same as a Time object in UTC" do
+      @obj.usec.should == 0
+      @obj.nsec.should == 0
+      @obj.subsec.should == 0
+      @obj.tv_usec.should == 0
+      @obj.tv_nsec.should == 0
 
-        time_loaded.zone.should == "Asia/Colombo"
-        time_loaded.utc_offset.should == 5*3600+30*60
-      end
+      @obj.utc_offset.should == 0
+      @obj.zone.should == "UTC"
+      @obj.isdst.should == Time.new.utc.isdst
+    end
+  end
 
-      it "cannot marshal Time if #name method isn't implemented" do
-        zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
-        time = Time.new(2000, 1, 1, 12, 0, 0, zone)
+  context "#name method" do
+    it "uses the optional #name method for marshaling" do
+      zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
+      time = Time.new(2000, 1, 1, 12, 0, 0, zone)
+      time_loaded = Marshal.load(Marshal.dump(time))
 
-        -> {
-          Marshal.dump(time)
-        }.should raise_error(NoMethodError, /undefined method `name' for/)
-      end
+      time_loaded.zone.should == "Asia/Colombo"
+      time_loaded.utc_offset.should == 5*3600+30*60
     end
 
-    it "the #abbr method is used by '%Z' in #strftime" do
-      zone = TimeSpecs::TimezoneWithAbbr.new(name: "Asia/Colombo")
+    it "cannot marshal Time if #name method isn't implemented" do
+      zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
       time = Time.new(2000, 1, 1, 12, 0, 0, zone)
 
-      time.strftime("%Z").should == "MMT"
+      -> {
+        Marshal.dump(time)
+      }.should raise_error(NoMethodError, /undefined method `name' for/)
     end
+  end
 
-    # At loading marshaled data, a timezone name will be converted to a timezone object
-    # by find_timezone class method, if the method is defined.
-    # Similarly, that class method will be called when a timezone argument does not have
-    # the necessary methods mentioned above.
-    context "subject's class implements .find_timezone method" do
-      it "calls .find_timezone to build a time object at loading marshaled data" do
-        zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
-        time = TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, zone)
-        time_loaded = Marshal.load(Marshal.dump(time))
-
-        time_loaded.zone.should be_kind_of TimeSpecs::TimezoneWithName
-        time_loaded.zone.name.should == "Asia/Colombo"
-        time_loaded.utc_offset.should == 5*3600+30*60
-      end
+  it "the #abbr method is used by '%Z' in #strftime" do
+    zone = TimeSpecs::TimezoneWithAbbr.new(name: "Asia/Colombo")
+    time = Time.new(2000, 1, 1, 12, 0, 0, zone)
 
-      it "calls .find_timezone to build a time object if passed zone name as a timezone argument" do
-        time = TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, "Asia/Colombo")
-        time.zone.should be_kind_of TimeSpecs::TimezoneWithName
-        time.zone.name.should == "Asia/Colombo"
+    time.strftime("%Z").should == "MMT"
+  end
 
-        time = TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, "some invalid zone name")
-        time.zone.should be_kind_of TimeSpecs::TimezoneWithName
-        time.zone.name.should == "some invalid zone name"
-      end
+  # At loading marshaled data, a timezone name will be converted to a timezone object
+  # by find_timezone class method, if the method is defined.
+  # Similarly, that class method will be called when a timezone argument does not have
+  # the necessary methods mentioned above.
+  context "subject's class implements .find_timezone method" do
+    it "calls .find_timezone to build a time object at loading marshaled data" do
+      zone = TimeSpecs::TimezoneWithName.new(name: "Asia/Colombo")
+      time = TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, zone)
+      time_loaded = Marshal.load(Marshal.dump(time))
+
+      time_loaded.zone.should be_kind_of TimeSpecs::TimezoneWithName
+      time_loaded.zone.name.should == "Asia/Colombo"
+      time_loaded.utc_offset.should == 5*3600+30*60
+    end
 
-      it "does not call .find_timezone if passed any not string/numeric/timezone timezone argument" do
-        [Object.new, [], {}, :"some zone"].each do |zone|
-          -> {
-            TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, zone)
-          }.should raise_error(TypeError, /can't convert \w+ into an exact number/)
-        end
+    it "calls .find_timezone to build a time object if passed zone name as a timezone argument" do
+      time = TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, "Asia/Colombo")
+      time.zone.should be_kind_of TimeSpecs::TimezoneWithName
+      time.zone.name.should == "Asia/Colombo"
+
+      time = TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, "some invalid zone name")
+      time.zone.should be_kind_of TimeSpecs::TimezoneWithName
+      time.zone.name.should == "some invalid zone name"
+    end
+
+    it "does not call .find_timezone if passed any not string/numeric/timezone timezone argument" do
+      [Object.new, [], {}, :"some zone"].each do |zone|
+        -> {
+          TimeSpecs::TimeWithFindTimezone.new(2000, 1, 1, 12, 0, 0, zone)
+        }.should raise_error(TypeError, /can't convert \w+ into an exact number/)
       end
     end
   end
diff --git a/spec/ruby/core/time/plus_spec.rb b/spec/ruby/core/time/plus_spec.rb
index c59d9a32bb..642393b615 100644
--- a/spec/ruby/core/time/plus_spec.rb
+++ b/spec/ruby/core/time/plus_spec.rb
@@ -56,14 +56,12 @@ describe "Time#+" do
     time_with_zone.zone.should == (time_with_zone + 1).zone
   end
 
-  ruby_version_is "2.6" do
-    context "zone is a timezone object" do
-      it "preserves time zone" do
-        zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
-        time = Time.new(2012, 1, 1, 12, 0, 0, zone) + 1
-
-        time.zone.should == zone
-      end
+  context "zone is a timezone object" do
+    it "preserves time zone" do
+      zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
+      time = Time.new(2012, 1, 1, 12, 0, 0, zone) + 1
+
+      time.zone.should == zone
     end
   end
 
diff --git a/spec/ruby/core/time/succ_spec.rb b/spec/ruby/core/time/succ_spec.rb
index fa6343f8e2..e8249059d1 100644
--- a/spec/ruby/core/time/succ_spec.rb
+++ b/spec/ruby/core/time/succ_spec.rb
@@ -27,14 +27,12 @@ ruby_version_is ""..."3.0" do
       }.should complain(/Time#succ is obsolete/)
     end
 
-    ruby_version_is "2.6" do
-      context "zone is a timezone object" do
-        it "preserves time zone" do
-          zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
-          time = Time.new(2012, 1, 1, 12, 0, 0, zone) - 1
-
-          time.zone.should == zone
-        end
+    context "zone is a timezone object" do
+      it "preserves time zone" do
+        zone = TimeSpecs::Timezone.new(offset: (5*3600+30*60))
+        time = Time.new(2012, 1, 1, 12, 0, 0, zone) - 1
+
+        time.zone.should == zone
       end
     end
   end
diff --git a/spec/ruby/core/tracepoint/enable_spec.rb b/spec/ruby/core/tracepoint/enable_spec.rb
index 50fded90e4..ab392c7583 100644
--- a/spec/ruby/core/tracepoint/enable_spec.rb
+++ b/spec/ruby/core/tracepoint/enable_spec.rb
@@ -161,65 +161,112 @@ describe 'TracePoint#enable' do
     end
   end
 
-  ruby_version_is "2.6" do
-    describe 'target: option' do
-      before :each do
-        ScratchPad.record []
+  describe 'target: option' do
+    before :each do
+      ScratchPad.record []
+    end
+
+    it 'enables trace point for specific location' do
+      trace = TracePoint.new(:call) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.method_id
       end
 
-      it 'enables trace point for specific location' do
-        trace = TracePoint.new(:call) do |tp|
-          next unless TracePointSpec.target_thread?
-          ScratchPad << tp.method_id
-        end
+      obj = Object.new
+      def obj.foo; end
+      def obj.bar; end
 
-        obj = Object.new
-        def obj.foo; end
-        def obj.bar; end
+      trace.enable(target: obj.method(:foo)) do
+        obj.foo
+        obj.bar
+      end
 
-        trace.enable(target: obj.method(:foo)) do
-          obj.foo
-          obj.bar
-        end
+      ScratchPad.recorded.should == [:foo]
+    end
 
-        ScratchPad.recorded.should == [:foo]
+    it 'traces all the events triggered in specified location' do
+      trace = TracePoint.new(:line, :call, :return, :b_call, :b_return) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.event
       end
 
-      it 'traces all the events triggered in specified location' do
-        trace = TracePoint.new(:line, :call, :return, :b_call, :b_return) do |tp|
-          next unless TracePointSpec.target_thread?
-          ScratchPad << tp.event
-        end
+      obj = Object.new
+      def obj.foo
+        bar
+        -> {}.call
+      end
+      def obj.bar; end
 
-        obj = Object.new
-        def obj.foo
-          bar
-          -> {}.call
+      trace.enable(target: obj.method(:foo)) do
+        obj.foo
+      end
+
+      ScratchPad.recorded.uniq.sort.should == [:call, :return, :b_call, :b_return, :line].sort
+    end
+
+    it 'does not trace events in nested locations' do
+      trace = TracePoint.new(:call) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.method_id
+      end
+
+      obj = Object.new
+      def obj.foo
+        bar
+      end
+      def obj.bar
+        baz
+      end
+      def obj.baz
+      end
+
+      trace.enable(target: obj.method(:foo)) do
+        obj.foo
+      end
+
+      ScratchPad.recorded.should == [:foo]
+    end
+
+    it "traces some events in nested blocks" do
+      klass = Class.new do
+        def foo
+          1.times do
+            1.times do
+              bar do
+              end
+            end
+          end
         end
-        def obj.bar; end
 
-        trace.enable(target: obj.method(:foo)) do
-          obj.foo
+        def bar(&blk)
+          blk.call
         end
+      end
+
+      trace = TracePoint.new(:b_call) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.lineno
+      end
+
+      obj = klass.new
+      _, lineno = obj.method(:foo).source_location
 
-        ScratchPad.recorded.uniq.sort.should == [:call, :return, :b_call, :b_return, :line].sort
+      trace.enable(target: obj.method(:foo)) do
+        obj.foo
       end
 
-      it 'does not trace events in nested locations' do
+      ScratchPad.recorded.should == (lineno+1..lineno+3).to_a
+    end
+
+    describe 'option value' do
+      it 'accepts Method' do
         trace = TracePoint.new(:call) do |tp|
           next unless TracePointSpec.target_thread?
           ScratchPad << tp.method_id
         end
 
         obj = Object.new
-        def obj.foo
-          bar
-        end
-        def obj.bar
-          baz
-        end
-        def obj.baz
-        end
+        def obj.foo; end
 
         trace.enable(target: obj.method(:foo)) do
           obj.foo
@@ -228,324 +275,275 @@ describe 'TracePoint#enable' do
         ScratchPad.recorded.should == [:foo]
       end
 
-      it "traces some events in nested blocks" do
+      it 'accepts UnboundMethod' do
+        trace = TracePoint.new(:call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << tp.method_id
+        end
+
         klass = Class.new do
-          def foo
-            1.times do
-              1.times do
-                bar do
-                end
-              end
-            end
-          end
+          def foo; end
+        end
 
-          def bar(&blk)
-            blk.call
-          end
+        unbound_method = klass.instance_method(:foo)
+        trace.enable(target: unbound_method) do
+          klass.new.foo
         end
 
+        ScratchPad.recorded.should == [:foo]
+      end
+
+      it 'accepts Proc' do
         trace = TracePoint.new(:b_call) do |tp|
           next unless TracePointSpec.target_thread?
           ScratchPad << tp.lineno
         end
 
-        obj = klass.new
-        _, lineno = obj.method(:foo).source_location
+        block = proc {}
+        _, lineno = block.source_location
 
-        trace.enable(target: obj.method(:foo)) do
-          obj.foo
+        trace.enable(target: block) do
+          block.call
         end
 
-        ScratchPad.recorded.should == (lineno+1..lineno+3).to_a
+        ScratchPad.recorded.should == [lineno]
+        lineno.should be_kind_of(Integer)
       end
+    end
 
-      describe 'option value' do
-        it 'accepts Method' do
-          trace = TracePoint.new(:call) do |tp|
-            next unless TracePointSpec.target_thread?
-            ScratchPad << tp.method_id
-          end
-
-          obj = Object.new
-          def obj.foo; end
+    it "raises ArgumentError if target object cannot trigger specified event" do
+      trace = TracePoint.new(:call) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.method_id
+      end
 
-          trace.enable(target: obj.method(:foo)) do
-            obj.foo
-          end
+      block = proc {}
 
-          ScratchPad.recorded.should == [:foo]
+      -> {
+        trace.enable(target: block) do
+          block.call # triggers :b_call and :b_return events
         end
+      }.should raise_error(ArgumentError, /can not enable any hooks/)
+    end
 
-        it 'accepts UnboundMethod' do
-          trace = TracePoint.new(:call) do |tp|
-            next unless TracePointSpec.target_thread?
-            ScratchPad << tp.method_id
-          end
-
-          klass = Class.new do
-            def foo; end
-          end
-
-          unbound_method = klass.instance_method(:foo)
-          trace.enable(target: unbound_method) do
-            klass.new.foo
-          end
+    it "raises ArgumentError if passed not Method/UnboundMethod/Proc" do
+      trace = TracePoint.new(:call) {}
 
-          ScratchPad.recorded.should == [:foo]
+      -> {
+        trace.enable(target: Object.new) do
         end
+      }.should raise_error(ArgumentError, /specified target is not supported/)
+    end
 
-        it 'accepts Proc' do
-          trace = TracePoint.new(:b_call) do |tp|
-            next unless TracePointSpec.target_thread?
-            ScratchPad << tp.lineno
+    context "nested enabling and disabling" do
+      it "raises ArgumentError if trace point already enabled with target is re-enabled with target" do
+        trace = TracePoint.new(:b_call) {}
+
+        -> {
+          trace.enable(target: -> {}) do
+            trace.enable(target: -> {}) do
+            end
           end
+        }.should raise_error(ArgumentError, /can't nest-enable a targett?ing TracePoint/)
+      end
 
-          block = proc {}
-          _, lineno = block.source_location
+      it "raises ArgumentError if trace point already enabled without target is re-enabled with target" do
+        trace = TracePoint.new(:b_call) {}
 
-          trace.enable(target: block) do
-            block.call
+        -> {
+          trace.enable do
+            trace.enable(target: -> {}) do
+            end
           end
-
-          ScratchPad.recorded.should == [lineno]
-          lineno.should be_kind_of(Integer)
-        end
+        }.should raise_error(ArgumentError, /can't nest-enable a targett?ing TracePoint/)
       end
 
-      it "raises ArgumentError if target object cannot trigger specified event" do
-        trace = TracePoint.new(:call) do |tp|
-          next unless TracePointSpec.target_thread?
-          ScratchPad << tp.method_id
-        end
-
-        block = proc {}
+      it "raises ArgumentError if trace point already enabled with target is re-enabled without target" do
+        trace = TracePoint.new(:b_call) {}
 
         -> {
-          trace.enable(target: block) do
-            block.call # triggers :b_call and :b_return events
+          trace.enable(target: -> {}) do
+            trace.enable do
+            end
           end
-        }.should raise_error(ArgumentError, /can not enable any hooks/)
+        }.should raise_error(ArgumentError, /can't nest-enable a targett?ing TracePoint/)
       end
 
-      it "raises ArgumentError if passed not Method/UnboundMethod/Proc" do
-        trace = TracePoint.new(:call) {}
+      it "raises ArgumentError if trace point already enabled with target is disabled with block" do
+        trace = TracePoint.new(:b_call) {}
 
         -> {
-          trace.enable(target: Object.new) do
+          trace.enable(target: -> {}) do
+            trace.disable do
+            end
           end
-        }.should raise_error(ArgumentError, /specified target is not supported/)
+        }.should raise_error(ArgumentError, /can't disable a targett?ing TracePoint in a block/)
       end
 
-      context "nested enabling and disabling" do
-        it "raises ArgumentError if trace point already enabled with target is re-enabled with target" do
-          trace = TracePoint.new(:b_call) {}
+      it "traces events when trace point with target is enabled in another trace point enabled without target" do
+        trace_outer = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << :outer
+        end
 
-          -> {
-            trace.enable(target: -> {}) do
-              trace.enable(target: -> {}) do
-              end
-            end
-          }.should raise_error(ArgumentError, /can't nest-enable a targett?ing TracePoint/)
+        trace_inner = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << :inner
         end
 
-        it "raises ArgumentError if trace point already enabled without target is re-enabled with target" do
-          trace = TracePoint.new(:b_call) {}
+        target = -> {}
 
-          -> {
-            trace.enable do
-              trace.enable(target: -> {}) do
-              end
-            end
-          }.should raise_error(ArgumentError, /can't nest-enable a targett?ing TracePoint/)
+        trace_outer.enable do
+          trace_inner.enable(target: target) do
+            target.call
+          end
         end
 
-        it "raises ArgumentError if trace point already enabled with target is re-enabled without target" do
-          trace = TracePoint.new(:b_call) {}
+        ScratchPad.recorded.should == [:outer, :outer, :outer, :inner]
+      end
 
-          -> {
-            trace.enable(target: -> {}) do
-              trace.enable do
-              end
-            end
-          }.should raise_error(ArgumentError, /can't nest-enable a targett?ing TracePoint/)
+      it "traces events when trace point with target is enabled in another trace point enabled with target" do
+        trace_outer = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << :outer
         end
 
-        it "raises ArgumentError if trace point already enabled with target is disabled with block" do
-          trace = TracePoint.new(:b_call) {}
-
-          -> {
-            trace.enable(target: -> {}) do
-              trace.disable do
-              end
-            end
-          }.should raise_error(ArgumentError, /can't disable a targett?ing TracePoint in a block/)
+        trace_inner = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << :inner
         end
 
-        it "traces events when trace point with target is enabled in another trace point enabled without target" do
-          trace_outer = TracePoint.new(:b_call) do |tp|
-            next unless TracePointSpec.target_thread?
-            ScratchPad << :outer
-          end
+        target = -> {}
 
-          trace_inner = TracePoint.new(:b_call) do |tp|
-            next unless TracePointSpec.target_thread?
-            ScratchPad << :inner
+        trace_outer.enable(target: target) do
+          trace_inner.enable(target: target) do
+            target.call
           end
+        end
 
-          target = -> {}
-
-          trace_outer.enable do
-            trace_inner.enable(target: target) do
-              target.call
-            end
-          end
+        ScratchPad.recorded.should == [:inner, :outer]
+      end
 
-          ScratchPad.recorded.should == [:outer, :outer, :outer, :inner]
+      it "traces events when trace point without target is enabled in another trace point enabled with target" do
+        trace_outer = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << :outer
         end
 
-        it "traces events when trace point with target is enabled in another trace point enabled with target" do
-          trace_outer = TracePoint.new(:b_call) do |tp|
-            next unless TracePointSpec.target_thread?
-            ScratchPad << :outer
-          end
-
-          trace_inner = TracePoint.new(:b_call) do |tp|
-            next unless TracePointSpec.target_thread?
-            ScratchPad << :inner
-          end
+        trace_inner = TracePoint.new(:b_call) do |tp|
+          next unless TracePointSpec.target_thread?
+          ScratchPad << :inner
+        end
 
-          target = -> {}
+        target = -> {}
 
-          trace_outer.enable(target: target) do
-            trace_inner.enable(target: target) do
-              target.call
-            end
+        trace_outer.enable(target: target) do
+          trace_inner.enable do
+            target.call
           end
-
-          ScratchPad.recorded.should == [:inner, :outer]
         end
 
-        it "traces events when trace point without target is enabled in another trace point enabled with target" do
-          trace_outer = TracePoint.new(:b_call) do |tp|
-            next unless TracePointSpec.target_thread?
-            ScratchPad << :outer
-          end
+        ScratchPad.recorded.should == [:inner, :inner, :outer]
+      end
+    end
+  end
 
-          trace_inner = TracePoint.new(:b_call) do |tp|
-            next unless TracePointSpec.target_thread?
-            ScratchPad << :inner
-          end
+  describe 'target_line: option' do
+    before :each do
+      ScratchPad.record []
+    end
 
-          target = -> {}
+    it "traces :line events only on specified line of code" do
+      trace = TracePoint.new(:line) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.lineno
+      end
 
-          trace_outer.enable(target: target) do
-            trace_inner.enable do
-              target.call
-            end
-          end
+      target = -> {
+        x = 1
+        y = 2      # <= this line is target
+        z = x + y
+      }
+      _, lineno = target.source_location
+      target_line = lineno + 2
 
-          ScratchPad.recorded.should == [:inner, :inner, :outer]
-        end
+      trace.enable(target_line: target_line, target: target) do
+        target.call
       end
+
+      ScratchPad.recorded.should == [target_line]
     end
 
-    describe 'target_line: option' do
-      before :each do
-        ScratchPad.record []
-      end
+    it "raises ArgumentError if :target option isn't specified" do
+      trace = TracePoint.new(:line) {}
 
-      it "traces :line events only on specified line of code" do
-        trace = TracePoint.new(:line) do |tp|
-          next unless TracePointSpec.target_thread?
-          ScratchPad << tp.lineno
+      -> {
+        trace.enable(target_line: 67) do
         end
+      }.should raise_error(ArgumentError, /only target_line is specified/)
+    end
+
+    it "raises ArgumentError if :line event isn't registered" do
+      trace = TracePoint.new(:call) {}
 
-        target = -> {
-          x = 1
-          y = 2      # <= this line is target
-          z = x + y
-        }
-        _, lineno = target.source_location
-        target_line = lineno + 2
+      target = -> {
+        x = 1
+        y = 2     # <= this line is target
+        z = x + y
+      }
+      _, lineno = target.source_location
+      target_line = lineno + 2
 
+      -> {
         trace.enable(target_line: target_line, target: target) do
-          target.call
         end
+      }.should raise_error(ArgumentError, /target_line is specified, but line event is not specified/)
+    end
 
-        ScratchPad.recorded.should == [target_line]
-      end
-
-      it "raises ArgumentError if :target option isn't specified" do
-        trace = TracePoint.new(:line) {}
-
-        -> {
-          trace.enable(target_line: 67) do
-          end
-        }.should raise_error(ArgumentError, /only target_line is specified/)
-      end
-
-      it "raises ArgumentError if :line event isn't registered" do
-        trace = TracePoint.new(:call) {}
+    it "raises ArgumentError if :target_line value is out of target code lines range" do
+      trace = TracePoint.new(:line) {}
 
-        target = -> {
-          x = 1
-          y = 2     # <= this line is target
-          z = x + y
-        }
-        _, lineno = target.source_location
-        target_line = lineno + 2
+      -> {
+        trace.enable(target_line: 1, target: -> { }) do
+        end
+      }.should raise_error(ArgumentError, /can not enable any hooks/)
+    end
 
-        -> {
-          trace.enable(target_line: target_line, target: target) do
-          end
-        }.should raise_error(ArgumentError, /target_line is specified, but line event is not specified/)
-      end
+    it "raises TypeError if :target_line value couldn't be coerced to Integer" do
+      trace = TracePoint.new(:line) {}
 
-      it "raises ArgumentError if :target_line value is out of target code lines range" do
-        trace = TracePoint.new(:line) {}
+      -> {
+        trace.enable(target_line: Object.new, target: -> { }) do
+        end
+      }.should raise_error(TypeError, /no implicit conversion of \w+? into Integer/)
+    end
 
-        -> {
-          trace.enable(target_line: 1, target: -> { }) do
-          end
-        }.should raise_error(ArgumentError, /can not enable any hooks/)
-      end
+    it "raises ArgumentError if :target_line value is negative" do
+      trace = TracePoint.new(:line) {}
 
-      it "raises TypeError if :target_line value couldn't be coerced to Integer" do
-        trace = TracePoint.new(:line) {}
+      -> {
+        trace.enable(target_line: -2, target: -> { }) do
+        end
+      }.should raise_error(ArgumentError, /can not enable any hooks/)
+    end
 
-        -> {
-          trace.enable(target_line: Object.new, target: -> { }) do
-          end
-        }.should raise_error(TypeError, /no implicit conversion of \w+? into Integer/)
+    it "accepts value that could be coerced to Integer" do
+      trace = TracePoint.new(:line) do |tp|
+        next unless TracePointSpec.target_thread?
+        ScratchPad << tp.lineno
       end
 
-      it "raises ArgumentError if :target_line value is negative" do
-        trace = TracePoint.new(:line) {}
+      target = -> {
+        x = 1         #  <= this line is target
+      }
+      _, lineno = target.source_location
+      target_line = lineno + 1
 
-        -> {
-          trace.enable(target_line: -2, target: -> { }) do
-          end
-        }.should raise_error(ArgumentError, /can not enable any hooks/)
+      trace.enable(target_line: target_line.to_r, target: target) do
+        target.call
       end
 
-      it "accepts value that could be coerced to Integer" do
-        trace = TracePoint.new(:line) do |tp|
-          next unless TracePointSpec.target_thread?
-          ScratchPad << tp.lineno
-        end
-
-        target = -> {
-          x = 1         #  <= this line is target
-        }
-        _, lineno = target.source_location
-        target_line = lineno + 1
-
-        trace.enable(target_line: target_line.to_r, target: target) do
-          target.call
-        end
-
-        ScratchPad.recorded.should == [target_line]
-      end
+      ScratchPad.recorded.should == [target_line]
     end
   end
 end
diff --git a/spec/ruby/core/tracepoint/eval_script_spec.rb b/spec/ruby/core/tracepoint/eval_script_spec.rb
index ccf7fb5975..7ec53e7094 100644
--- a/spec/ruby/core/tracepoint/eval_script_spec.rb
+++ b/spec/ruby/core/tracepoint/eval_script_spec.rb
@@ -1,25 +1,23 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-ruby_version_is "2.6" do
-  describe "TracePoint#eval_script" do
-    it "is the evald source code" do
-      ScratchPad.record []
+describe "TracePoint#eval_script" do
+  it "is the evald source code" do
+    ScratchPad.record []
 
-      script = <<-CODE
-        def foo
-          p :hello
-        end
-      CODE
-
-      TracePoint.new(:script_compiled) do |e|
-        next unless TracePointSpec.target_thread?
-        ScratchPad << e.eval_script
-      end.enable do
-        eval script
+    script = <<-CODE
+      def foo
+        p :hello
       end
+    CODE
 
-      ScratchPad.recorded.should == [script]
+    TracePoint.new(:script_compiled) do |e|
+      next unless TracePointSpec.target_thread?
+      ScratchPad << e.eval_script
+    end.enable do
+      eval script
     end
+
+    ScratchPad.recorded.should == [script]
   end
 end
diff --git a/spec/ruby/core/tracepoint/parameters_spec.rb b/spec/ruby/core/tracepoint/parameters_spec.rb
index 3a2cdd7750..82aee3caa4 100644
--- a/spec/ruby/core/tracepoint/parameters_spec.rb
+++ b/spec/ruby/core/tracepoint/parameters_spec.rb
@@ -1,30 +1,28 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
-ruby_version_is "2.6" do
-  describe 'TracePoint#parameters' do
-    it 'returns the parameters of block' do
-      f = proc {|x, y, z| }
-      parameters = nil
-      TracePoint.new(:b_call) { |tp|
-        next unless TracePointSpec.target_thread?
-        parameters = tp.parameters
-      }.enable do
-        f.call
-        parameters.should == [[:opt, :x], [:opt, :y], [:opt, :z]]
-      end
+describe 'TracePoint#parameters' do
+  it 'returns the parameters of block' do
+    f = proc {|x, y, z| }
+    parameters = nil
+    TracePoint.new(:b_call) { |tp|
+      next unless TracePointSpec.target_thread?
+      parameters = tp.parameters
+    }.enable do
+      f.call
+      parameters.should == [[:opt, :x], [:opt, :y], [:opt, :z]]
     end
+  end
 
-    it 'returns the parameters of lambda block' do
-      f = -> x, y, z { }
-      parameters = nil
-      TracePoint.new(:b_call) { |tp|
-        next unless TracePointSpec.target_thread?
-        parameters = tp.parameters
-      }.enable do
-        f.call(1, 2, 3)
-        parameters.should == [[:req, :x], [:req, :y], [:req, :z]]
-      end
+  it 'returns the parameters of lambda block' do
+    f = -> x, y, z { }
+    parameters = nil
+    TracePoint.new(:b_call) { |tp|
+      next unless TracePointSpec.target_thread?
+      parameters = tp.parameters
+    }.enable do
+      f.call(1, 2, 3)
+      parameters.should == [[:req, :x], [:req, :y], [:req, :z]]
     end
   end
 end
diff --git a/spec/ruby/language/constants_spec.rb b/spec/ruby/language/constants_spec.rb
index 760b9d4a24..03f1272401 100644
--- a/spec/ruby/language/constants_spec.rb
+++ b/spec/ruby/language/constants_spec.rb
@@ -432,17 +432,15 @@ describe "Module#private_constant marked constants" do
     -> {mod::Foo}.should raise_error(NameError)
   end
 
-  ruby_version_is "2.6" do
-    it "sends #const_missing to the original class or module" do
-      mod = Module.new
-      mod.const_set :Foo, true
-      mod.send :private_constant, :Foo
-      def mod.const_missing(name)
-        name == :Foo ? name : super
-      end
-
-      mod::Foo.should == :Foo
+  it "sends #const_missing to the original class or module" do
+    mod = Module.new
+    mod.const_set :Foo, true
+    mod.send :private_constant, :Foo
+    def mod.const_missing(name)
+      name == :Foo ? name : super
     end
+
+    mod::Foo.should == :Foo
   end
 
   describe "in a module" do
@@ -713,20 +711,10 @@ describe 'Allowed characters' do
     end.should raise_error(NameError, /wrong constant name/)
   end
 
-  ruby_version_is ""..."2.6" do
-    it 'does not allow not ASCII upcased characters at the beginning' do
-      -> do
-        Module.new.const_set("ἍBB", 1)
-      end.should raise_error(NameError, /wrong constant name/)
-    end
-  end
-
-  ruby_version_is "2.6" do
-    it 'allows not ASCII upcased characters at the beginning' do
-      mod = Module.new
-      mod.const_set("ἍBB", 1)
+  it 'allows not ASCII upcased characters at the beginning' do
+    mod = Module.new
+    mod.const_set("ἍBB", 1)
 
-      eval("mod::ἍBB").should == 1
-    end
+    eval("mod::ἍBB").should == 1
   end
 end
diff --git a/spec/ruby/language/delegation_spec.rb b/spec/ruby/language/delegation_spec.rb
index ac7b511f65..8e4183cbcc 100644
--- a/spec/ruby/language/delegation_spec.rb
+++ b/spec/ruby/language/delegation_spec.rb
@@ -39,3 +39,30 @@ ruby_version_is "2.7" do
     end
   end
 end
+
+ruby_version_is "2.7.3" do
+  describe "delegation with def(x, ...)" do
+    it "delegates rest and kwargs" do
+      a = Class.new(DelegationSpecs::Target)
+      a.class_eval(<<-RUBY)
+        def delegate(x, ...)
+          target(...)
+        end
+      RUBY
+
+      a.new.delegate(0, 1, b: 2).should == [[1], {b: 2}]
+    end
+
+    it "delegates block" do
+      a = Class.new(DelegationSpecs::Target)
+      a.class_eval(<<-RUBY)
+        def delegate_block(x, ...)
+          target_block(...)
+        end
+      RUBY
+
+      a.new.delegate_block(0, 1, b: 2) { |x| x }.should == [{b: 2}, [1]]
+    end
+
+  end
+end
diff --git a/spec/ruby/language/hash_spec.rb b/spec/ruby/language/hash_spec.rb
index 9b2e5a2dc7..f99ff8ab3f 100644
--- a/spec/ruby/language/hash_spec.rb
+++ b/spec/ruby/language/hash_spec.rb
@@ -58,11 +58,16 @@ describe "Hash literal" do
     }.should complain(/key 1000 is duplicated|duplicated key/)
     @h.keys.size.should == 1
     @h.should == {1000 => :foo}
-    -> {
-      @h = eval "{1.0 => :bar, 1.0 => :foo}"
-    }.should complain(/key 1.0 is duplicated|duplicated key/)
-    @h.keys.size.should == 1
-    @h.should == {1.0 => :foo}
+  end
+
+  ruby_version_is "3.1" do
+    it "checks duplicated float keys on initialization" do
+      -> {
+        @h = eval "{1.0 => :bar, 1.0 => :foo}"
+      }.should complain(/key 1.0 is duplicated|duplicated key/)
+      @h.keys.size.should == 1
+      @h.should == {1.0 => :foo}
+    end
   end
 
   it "accepts a hanging comma" do
diff --git a/spec/ruby/language/lambda_spec.rb b/spec/ruby/language/lambda_spec.rb
index 630817c909..6393fb5c47 100644
--- a/spec/ruby/language/lambda_spec.rb
+++ b/spec/ruby/language/lambda_spec.rb
@@ -22,14 +22,12 @@ describe "A lambda literal -> () { }" do
     -> { }.lambda?.should be_true
   end
 
-  ruby_version_is "2.6" do
-    it "may include a rescue clause" do
-      eval('-> do raise ArgumentError; rescue ArgumentError; 7; end').should be_an_instance_of(Proc)
-    end
+  it "may include a rescue clause" do
+    eval('-> do raise ArgumentError; rescue ArgumentError; 7; end').should be_an_instance_of(Proc)
+  end
 
-    it "may include a ensure clause" do
-      eval('-> do 1; ensure; 2; end').should be_an_instance_of(Proc)
-    end
+  it "may include a ensure clause" do
+    eval('-> do 1; ensure; 2; end').should be_an_instance_of(Proc)
   end
 
   it "has its own scope for local variables" do
diff --git a/spec/ruby/language/range_spec.rb b/spec/ruby/language/range_spec.rb
index c0f90f84d6..79500c6b33 100644
--- a/spec/ruby/language/range_spec.rb
+++ b/spec/ruby/language/range_spec.rb
@@ -10,11 +10,9 @@ describe "Literal Ranges" do
     (1...10).should == Range.new(1, 10, true)
   end
 
-  ruby_version_is "2.6" do
-    it "creates endless ranges" do
-      eval("(1..)").should == Range.new(1, nil)
-      eval("(1...)").should == Range.new(1, nil, true)
-    end
+  it "creates endless ranges" do
+    (1..).should == Range.new(1, nil)
+    (1...).should == Range.new(1, nil, true)
   end
 
   ruby_version_is "2.7" do
diff --git a/spec/ruby/language/regexp_spec.rb b/spec/ruby/language/regexp_spec.rb
index def9bba5f7..f607fa6010 100644
--- a/spec/ruby/language/regexp_spec.rb
+++ b/spec/ruby/language/regexp_spec.rb
@@ -115,10 +115,11 @@ describe "Literal Regexps" do
     /foo.(?<=\d)/.match("fooA foo1").to_a.should == ["foo1"]
   end
 
-  # https://bugs.ruby-lang.org/issues/13671
-  it "raises a RegexpError for lookbehind with specific characters" do
-    r =  Regexp.new("(?<!dss)", Regexp::IGNORECASE)
-    -> { r =~ "✨" }.should raise_error(RegexpError)
+  ruby_bug "#13671", ""..."3.2" do # https://bugs.ruby-lang.org/issues/13671
+    it "handles a lookbehind with ss characters" do
+      r =  Regexp.new("(?<!dss)", Regexp::IGNORECASE)
+      r.should =~ "✨"
+    end
   end
 
   it "supports (?<! ) (negative lookbehind)" do
diff --git a/spec/ruby/language/rescue_spec.rb b/spec/ruby/language/rescue_spec.rb
index 1c78f3935a..4d164b38c6 100644
--- a/spec/ruby/language/rescue_spec.rb
+++ b/spec/ruby/language/rescue_spec.rb
@@ -238,34 +238,16 @@ describe "The rescue keyword" do
     ScratchPad.recorded.should == [:one, :else_ran, :ensure_ran, :outside_begin]
   end
 
-  ruby_version_is ''...'2.6' do
-    it "will execute an else block even without rescue and ensure" do
-      -> {
-        eval <<-ruby
-          begin
-            ScratchPad << :begin
-          else
-            ScratchPad << :else
-          end
-        ruby
-      }.should complain(/else without rescue is useless/)
-
-      ScratchPad.recorded.should == [:begin, :else]
-    end
-  end
-
-  ruby_version_is '2.6' do
-    it "raises SyntaxError when else is used without rescue and ensure" do
-      -> {
-        eval <<-ruby
-          begin
-            ScratchPad << :begin
-          else
-            ScratchPad << :else
-          end
-        ruby
-      }.should raise_error(SyntaxError, /else without rescue is useless/)
-    end
+  it "raises SyntaxError when else is used without rescue and ensure" do
+    -> {
+      eval <<-ruby
+        begin
+          ScratchPad << :begin
+        else
+          ScratchPad << :else
+        end
+      ruby
+    }.should raise_error(SyntaxError, /else without rescue is useless/)
   end
 
   it "will not execute an else block if an exception was raised" do
diff --git a/spec/ruby/language/safe_spec.rb b/spec/ruby/language/safe_spec.rb
index f3a7efc953..062381d729 100644
--- a/spec/ruby/language/safe_spec.rb
+++ b/spec/ruby/language/safe_spec.rb
@@ -2,10 +2,8 @@ require_relative '../spec_helper'
 
 describe "The $SAFE variable" do
   ruby_version_is ""..."2.7" do
-    ruby_version_is "2.6" do
-      after :each do
-        $SAFE = 0
-      end
+    after :each do
+      $SAFE = 0
     end
 
     it "is 0 by default" do
@@ -39,24 +37,12 @@ describe "The $SAFE variable" do
       end
     end
 
-    ruby_version_is ""..."2.6" do
-      it "cannot be set to values below 0" do
-        -> {
-          proc {
-            $SAFE = -100
-          }.call
-        }.should raise_error(SecurityError, /tried to downgrade safe level from 0 to -100/)
-      end
-    end
-
-    ruby_version_is "2.6" do
-      it "raises ArgumentError when set to values below 0" do
-        -> {
-          proc {
-            $SAFE = -100
-          }.call
-        }.should raise_error(ArgumentError, "$SAFE should be >= 0")
-      end
+    it "raises ArgumentError when set to values below 0" do
+      -> {
+        proc {
+          $SAFE = -100
+        }.call
+      }.should raise_error(ArgumentError, "$SAFE should be >= 0")
     end
 
     it "cannot be set to values above 4" do
@@ -67,61 +53,32 @@ describe "The $SAFE variable" do
       }.should raise_error(ArgumentError, /\$SAFE=2 to 4 are obsolete/)
     end
 
-    ruby_version_is ""..."2.6" do
-      it "cannot be manually lowered" do
-        proc {
-          $SAFE = 1
-          -> {
-            $SAFE = 0
-          }.should raise_error(SecurityError, /tried to downgrade safe level from 1 to 0/)
-        }.call
-      end
-
-      it "is automatically lowered when leaving a proc" do
-        $SAFE.should == 0
-        proc {
-          $SAFE = 1
-        }.call
-        $SAFE.should == 0
-      end
-
-      it "is automatically lowered when leaving a lambda" do
-        $SAFE.should == 0
-        -> {
-          $SAFE = 1
-        }.call
-        $SAFE.should == 0
-      end
+    it "can be manually lowered" do
+      $SAFE = 1
+      $SAFE = 0
+      $SAFE.should == 0
     end
 
-    ruby_version_is "2.6" do
-      it "can be manually lowered" do
+    it "is not Proc local" do
+      $SAFE.should == 0
+      proc {
         $SAFE = 1
-        $SAFE = 0
-        $SAFE.should == 0
-      end
-
-      it "is not Proc local" do
-        $SAFE.should == 0
-        proc {
-          $SAFE = 1
-        }.call
-        $SAFE.should == 1
-      end
-
-      it "is not lambda local" do
-        $SAFE.should == 0
-        -> {
-          $SAFE = 1
-        }.call
-        $SAFE.should == 1
-      end
+      }.call
+      $SAFE.should == 1
+    end
 
-      it "is global like regular global variables" do
-        Thread.new { $SAFE }.value.should == 0
+    it "is not lambda local" do
+      $SAFE.should == 0
+      -> {
         $SAFE = 1
-        Thread.new { $SAFE }.value.should == 1
-      end
+      }.call
+      $SAFE.should == 1
+    end
+
+    it "is global like regular global variables" do
+      Thread.new { $SAFE }.value.should == 0
+      $SAFE = 1
+      Thread.new { $SAFE }.value.should == 1
     end
 
     it "can be read when default from Thread#safe_level" do
diff --git a/spec/ruby/language/variables_spec.rb b/spec/ruby/language/variables_spec.rb
index ce072baa2c..7d6969e659 100644
--- a/spec/ruby/language/variables_spec.rb
+++ b/spec/ruby/language/variables_spec.rb
@@ -715,6 +715,18 @@ describe "Multiple assignment" do
       x.should == [1, 2, 3, 4, 5]
     end
 
+    it "can be used to swap array elements" do
+      a = [1, 2]
+      a[0], a[1] = a[1], a[0]
+      a.should == [2, 1]
+    end
+
+    it "can be used to swap range of array elements" do
+      a = [1, 2, 3, 4]
+      a[0, 2], a[2, 2] = a[2, 2], a[0, 2]
+      a.should == [3, 4, 1, 2]
+    end
+
     it "assigns RHS values to LHS constants" do
       module VariableSpecs
         MRHS_VALUES_1, MRHS_VALUES_2 = 1, 2
@@ -770,45 +782,30 @@ describe "A local variable assigned only within a conditional block" do
 end
 
 describe 'Local variable shadowing' do
-  ruby_version_is ""..."2.6" do
-    it "leads to warning in verbose mode" do
-      -> do
-        eval <<-CODE
-          a = [1, 2, 3]
-          a.each { |a| a = 3 }
-        CODE
-      end.should complain(/shadowing outer local variable/, verbose: true)
-    end
-  end
-
-  ruby_version_is "2.6" do
-    it "does not warn in verbose mode" do
-      result = nil
+  it "does not warn in verbose mode" do
+    result = nil
 
-      -> do
-        eval <<-CODE
-          a = [1, 2, 3]
-          result = a.map { |a| a = 3 }
-        CODE
-      end.should_not complain(verbose: true)
+    -> do
+      eval <<-CODE
+        a = [1, 2, 3]
+        result = a.map { |a| a = 3 }
+      CODE
+    end.should_not complain(verbose: true)
 
-      result.should == [3, 3, 3]
-    end
+    result.should == [3, 3, 3]
   end
 end
 
 describe 'Allowed characters' do
-  ruby_version_is "2.6" do
-    # new feature in 2.6 -- https://bugs.ruby-lang.org/issues/13770
-    it 'does not allow non-ASCII upcased characters at the beginning' do
-      -> do
-        eval <<-CODE
-          def test
-            ἍBB = 1
-          end
-        CODE
-      end.should raise_error(SyntaxError, /dynamic constant assignment/)
-    end
+  # new feature in 2.6 -- https://bugs.ruby-lang.org/issues/13770
+  it 'does not allow non-ASCII upcased characters at the beginning' do
+    -> do
+      eval <<-CODE
+        def test
+          ἍBB = 1
+        end
+      CODE
+    end.should raise_error(SyntaxError, /dynamic constant assignment/)
   end
 
   it 'allows non-ASCII lowercased characters at the beginning' do
diff --git a/spec/ruby/library/bigdecimal/BigDecimal_spec.rb b/spec/ruby/library/bigdecimal/BigDecimal_spec.rb
index d56c0a664b..43a779b420 100644
--- a/spec/ruby/library/bigdecimal/BigDecimal_spec.rb
+++ b/spec/ruby/library/bigdecimal/BigDecimal_spec.rb
@@ -56,22 +56,11 @@ describe "Kernel#BigDecimal" do
     BigDecimal(initial).should == BigDecimal("123")
   end
 
-  ruby_version_is ""..."2.6" do
-    it "ignores trailing garbage" do
-      BigDecimal("123E45ruby").should == BigDecimal("123E45")
-      BigDecimal("123x45").should == BigDecimal("123")
-      BigDecimal("123.4%E5").should == BigDecimal("123.4")
-      BigDecimal("1E2E3E4E5E").should == BigDecimal("100")
-    end
-  end
-
-  ruby_version_is "2.6" do
-    it "does not ignores trailing garbage" do
-      -> { BigDecimal("123E45ruby") }.should raise_error(ArgumentError)
-      -> { BigDecimal("123x45") }.should raise_error(ArgumentError)
-      -> { BigDecimal("123.4%E5") }.should raise_error(ArgumentError)
-      -> { BigDecimal("1E2E3E4E5E") }.should raise_error(ArgumentError)
-    end
+  it "does not ignores trailing garbage" do
+    -> { BigDecimal("123E45ruby") }.should raise_error(ArgumentError)
+    -> { BigDecimal("123x45") }.should raise_error(ArgumentError)
+    -> { BigDecimal("123.4%E5") }.should raise_error(ArgumentError)
+    -> { BigDecimal("1E2E3E4E5E") }.should raise_error(ArgumentError)
   end
 
   it "raises ArgumentError for invalid strings" do
@@ -83,24 +72,12 @@ describe "Kernel#BigDecimal" do
     BigDecimal(".123").should == BigDecimal("0.123")
   end
 
-  ruby_version_is ""..."2.6" do
-    it "allows for underscores in all parts" do
-      reference = BigDecimal("12345.67E89")
-
-      BigDecimal("12_345.67E89").should == reference
-      BigDecimal("1_2_3_4_5_._6____7_E89").should == reference
-      BigDecimal("12345_.67E_8__9_").should == reference
-    end
-  end
-
-  ruby_version_is "2.6" do
-    it "process underscores as Float()" do
-      reference = BigDecimal("12345.67E89")
+  it "process underscores as Float()" do
+    reference = BigDecimal("12345.67E89")
 
-      BigDecimal("12_345.67E89").should == reference
-      -> { BigDecimal("1_2_3_4_5_._6____7_E89") }.should raise_error(ArgumentError)
-      -> { BigDecimal("12345_.67E_8__9_") }.should raise_error(ArgumentError)
-    end
+    BigDecimal("12_345.67E89").should == reference
+    -> { BigDecimal("1_2_3_4_5_._6____7_E89") }.should raise_error(ArgumentError)
+    -> { BigDecimal("12345_.67E_8__9_") }.should raise_error(ArgumentError)
   end
 
   it "accepts NaN and [+-]Infinity" do
@@ -116,14 +93,12 @@ describe "Kernel#BigDecimal" do
     neg_inf.should < 0
   end
 
-  ruby_version_is "2.6" do
-    describe "with exception: false" do
-      it "returns nil for invalid strings" do
-        BigDecimal("invalid", exception: false).should be_nil
-        BigDecimal("0invalid", exception: false).should be_nil
-        BigDecimal("invalid0", exception: false).should be_nil
-        BigDecimal("0.", exception: false).should be_nil
-      end
+  describe "with exception: false" do
+    it "returns nil for invalid strings" do
+      BigDecimal("invalid", exception: false).should be_nil
+      BigDecimal("0invalid", exception: false).should be_nil
+      BigDecimal("invalid0", exception: false).should be_nil
+      BigDecimal("0.", exception: false).should be_nil
     end
   end
 
diff --git a/spec/ruby/library/bigdecimal/util_spec.rb b/spec/ruby/library/bigdecimal/util_spec.rb
index f41e131144..fc67fcf200 100644
--- a/spec/ruby/library/bigdecimal/util_spec.rb
+++ b/spec/ruby/library/bigdecimal/util_spec.rb
@@ -27,10 +27,8 @@ describe "BigDecimal's util method definitions" do
       Rational(22, 7).to_d(3).should == BigDecimal(3.14, 3)
     end
 
-    ruby_version_is "2.6" do
-      it "should define #to_d on nil" do
-        nil.to_d.should == BigDecimal(0)
-      end
+    it "should define #to_d on nil" do
+      nil.to_d.should == BigDecimal(0)
     end
   end
 
diff --git a/spec/ruby/library/erb/fixtures/classes.rb b/spec/ruby/library/erb/fixtures/classes.rb
index 03da889941..e07a6ed68d 100644
--- a/spec/ruby/library/erb/fixtures/classes.rb
+++ b/spec/ruby/library/erb/fixtures/classes.rb
@@ -1,9 +1,5 @@
 module ERBSpecs
   def self.new_erb(input, trim_mode: nil)
-    if ruby_version_is "2.6"
-      ERB.new(input, trim_mode: trim_mode)
-    else
-      ERB.new(input, nil, trim_mode)
-    end
+    ERB.new(input, trim_mode: trim_mode)
   end
 end
diff --git a/spec/ruby/library/erb/new_spec.rb b/spec/ruby/library/erb/new_spec.rb
index 3bb870dd3f..f18e25939e 100644
--- a/spec/ruby/library/erb/new_spec.rb
+++ b/spec/ruby/library/erb/new_spec.rb
@@ -36,12 +36,10 @@ END
     end
   end
 
-  ruby_version_is "2.6" do
-    it "warns invalid trim_mode" do
-      -> do
-        ERBSpecs.new_erb(@eruby_str, trim_mode: '')
-      end.should complain(/Invalid ERB trim mode/)
-    end
+  it "warns invalid trim_mode" do
+    -> do
+      ERBSpecs.new_erb(@eruby_str, trim_mode: '')
+    end.should complain(/Invalid ERB trim mode/)
   end
 
   it "removes '\n' when trim_mode is 1 or '>'" do
@@ -120,13 +118,8 @@ END
 
   it "changes '_erbout' variable name in the produced source" do
     input = @eruby_str
-    if RUBY_VERSION >= '2.6'
-      match_erbout = ERB.new(input, trim_mode: nil).src
-      match_buf = ERB.new(input, trim_mode: nil, eoutvar: 'buf').src
-    else
-      match_erbout = ERB.new(input, nil, nil).src
-      match_buf = ERB.new(input, nil, nil, 'buf').src
-    end
+    match_erbout = ERB.new(input, trim_mode: nil).src
+    match_buf = ERB.new(input, trim_mode: nil, eoutvar: 'buf').src
     match_erbout.gsub("_erbout", "buf").should == match_buf
   end
 
diff --git a/spec/ruby/library/matrix/antisymmetric_spec.rb b/spec/ruby/library/matrix/antisymmetric_spec.rb
index a0d1a5f69b..dcc3c30f3e 100644
--- a/spec/ruby/library/matrix/antisymmetric_spec.rb
+++ b/spec/ruby/library/matrix/antisymmetric_spec.rb
@@ -3,37 +3,35 @@ require_relative '../../spec_helper'
 ruby_version_is ""..."3.1" do
   require 'matrix'
 
-  ruby_version_is "2.6" do
-    describe "Matrix#antisymmetric?" do
-      it "returns true for an antisymmetric Matrix" do
-        Matrix[[0, -2, Complex(1, 3)], [2, 0, 5], [-Complex(1, 3), -5, 0]].antisymmetric?.should be_true
-      end
+  describe "Matrix#antisymmetric?" do
+    it "returns true for an antisymmetric Matrix" do
+      Matrix[[0, -2, Complex(1, 3)], [2, 0, 5], [-Complex(1, 3), -5, 0]].antisymmetric?.should be_true
+    end
 
-      it "returns true for a 0x0 empty matrix" do
-        Matrix.empty.antisymmetric?.should be_true
-      end
+    it "returns true for a 0x0 empty matrix" do
+      Matrix.empty.antisymmetric?.should be_true
+    end
 
-      it "returns false for non-antisymmetric matrices" do
-        [
-          Matrix[[1, 2, 3], [4, 5, 6], [7, 8, 9]],
-          Matrix[[1, -2, 3], [2, 0, 6], [-3, -6, 0]],  # wrong diagonal element
-          Matrix[[0, 2, -3], [2, 0, 6], [-3, 6, 0]]    # only signs wrong
-        ].each do |matrix|
-          matrix.antisymmetric?.should be_false
-        end
+    it "returns false for non-antisymmetric matrices" do
+      [
+        Matrix[[1, 2, 3], [4, 5, 6], [7, 8, 9]],
+        Matrix[[1, -2, 3], [2, 0, 6], [-3, -6, 0]],  # wrong diagonal element
+        Matrix[[0, 2, -3], [2, 0, 6], [-3, 6, 0]]    # only signs wrong
+      ].each do |matrix|
+        matrix.antisymmetric?.should be_false
       end
+    end
 
-      it "raises an error for rectangular matrices" do
-        [
-          Matrix[[0], [0]],
-          Matrix[[0, 0]],
-          Matrix.empty(0, 2),
-          Matrix.empty(2, 0),
-        ].each do |rectangular_matrix|
-          -> {
-            rectangular_matrix.antisymmetric?
-          }.should raise_error(Matrix::ErrDimensionMismatch)
-        end
+    it "raises an error for rectangular matrices" do
+      [
+        Matrix[[0], [0]],
+        Matrix[[0, 0]],
+        Matrix.empty(0, 2),
+        Matrix.empty(2, 0),
+      ].each do |rectangular_matrix|
+        -> {
+          rectangular_matrix.antisymmetric?
+        }.should raise_error(Matrix::ErrDimensionMismatch)
       end
     end
   end
diff --git a/spec/ruby/library/monitor/enter_spec.rb b/spec/ruby/library/monitor/enter_spec.rb
new file mode 100644
index 0000000000..f523c42087
--- /dev/null
+++ b/spec/ruby/library/monitor/enter_spec.rb
@@ -0,0 +1,28 @@
+require_relative '../../spec_helper'
+require 'monitor'
+
+describe "Monitor#enter" do
+  it "acquires the monitor" do
+    monitor = Monitor.new
+    10.times do
+      wait_q = Queue.new
+      continue_q = Queue.new
+
+      thread = Thread.new do
+        begin
+          monitor.enter
+          wait_q << true
+          continue_q.pop
+        ensure
+          monitor.exit
+        end
+      end
+
+      wait_q.pop
+      monitor.mon_locked?.should == true
+      continue_q << true
+      thread.join
+      monitor.mon_locked?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/library/monitor/new_cond_spec.rb b/spec/ruby/library/monitor/new_cond_spec.rb
new file mode 100644
index 0000000000..ec25d3f8a2
--- /dev/null
+++ b/spec/ruby/library/monitor/new_cond_spec.rb
@@ -0,0 +1,88 @@
+require_relative '../../spec_helper'
+require 'monitor'
+
+describe "Monitor#new_cond" do
+  it "creates a MonitorMixin::ConditionVariable" do
+    m = Monitor.new
+    c = m.new_cond
+    c.class.should == MonitorMixin::ConditionVariable
+  end
+
+  it 'returns a condition variable which can be waited on by a thread holding the monitor' do
+    m = Monitor.new
+    c = m.new_cond
+
+    10.times do
+
+      wait_q = Queue.new
+      thread = Thread.new do
+        m.synchronize do
+          wait_q << true
+          c.wait
+        end
+        :done
+      end
+
+      wait_q.pop
+
+      # Synchronize can't happen until the other thread is waiting.
+      m.synchronize { c.signal }
+
+      thread.join
+      thread.value.should == :done
+    end
+  end
+
+  it 'returns a condition variable which can be waited on by a thread holding the monitor inside multiple synchronize blocks' do
+    m = Monitor.new
+    c = m.new_cond
+
+    10.times do
+
+      wait_q = Queue.new
+      thread = Thread.new do
+        m.synchronize do
+          m.synchronize do
+            wait_q << true
+            c.wait
+          end
+        end
+        :done
+      end
+
+      wait_q.pop
+
+      #No need to wait here as we cannot synchronize until the other thread is waiting.
+      m.synchronize { c.signal }
+
+      thread.join
+      thread.value.should == :done
+    end
+  end
+
+  it 'returns a condition variable which can be signalled by a thread holding the monitor inside multiple synchronize blocks' do
+    m = Monitor.new
+    c = m.new_cond
+
+    10.times do
+
+      wait_q = Queue.new
+      thread = Thread.new do
+        m.synchronize do
+          wait_q << true
+          c.wait
+        end
+        :done
+      end
+
+      wait_q.pop
+
+      # Synchronize can't happen until the other thread is waiting.
+      m.synchronize { m.synchronize { c.signal } }
+
+      thread.join
+      thread.value.should == :done
+    end
+  end
+
+end
diff --git a/spec/ruby/library/monitor/synchronize_spec.rb b/spec/ruby/library/monitor/synchronize_spec.rb
index d851b98d6c..d78393eb3a 100644
--- a/spec/ruby/library/monitor/synchronize_spec.rb
+++ b/spec/ruby/library/monitor/synchronize_spec.rb
@@ -7,24 +7,35 @@ describe "Monitor#synchronize" do
 
     monitor = Monitor.new
     10.times do
-      locked = false
+      wait_q = Queue.new
+      continue_q = Queue.new
 
       thread = Thread.new do
         begin
           monitor.synchronize do
-            locked = true
+            wait_q << true
             # Do not wait here, we are trying to interrupt the ensure part of #synchronize
           end
-          sleep # wait for exception if it did not happen yet
+          continue_q.pop
         rescue exc_class
           monitor.should_not.mon_locked?
           :ok
         end
       end
 
-      Thread.pass until locked
+      wait_q.pop
       thread.raise exc_class, "interrupt"
+      continue_q << true
       thread.value.should == :ok
     end
   end
+
+  it "raises a LocalJumpError if not passed a block" do
+    -> { Monitor.new.synchronize }.should raise_error(LocalJumpError)
+  end
+
+  it "raises a thread error if the monitor is not owned on exiting the block" do
+    monitor = Monitor.new
+    -> { monitor.synchronize { monitor.exit } }.should raise_error(ThreadError)
+  end
 end
diff --git a/spec/ruby/library/monitor/try_enter_spec.rb b/spec/ruby/library/monitor/try_enter_spec.rb
new file mode 100644
index 0000000000..04b878f720
--- /dev/null
+++ b/spec/ruby/library/monitor/try_enter_spec.rb
@@ -0,0 +1,39 @@
+require_relative '../../spec_helper'
+require 'monitor'
+
+describe "Monitor#try_enter" do
+  it "will acquire a monitor not held by another thread" do
+    monitor = Monitor.new
+    10.times do
+
+      thread = Thread.new do
+        val = monitor.try_enter
+        monitor.exit if val
+        val
+      end
+
+      thread.join
+      thread.value.should == true
+    end
+  end
+
+  it "will not acquire a monitor already held by another thread" do
+    monitor = Monitor.new
+    10.times do
+      monitor.enter
+      begin
+        thread = Thread.new do
+          val = monitor.try_enter
+          monitor.exit if val
+          val
+        end
+
+        thread.join
+        thread.value.should == false
+      ensure
+        monitor.exit
+      end
+      monitor.mon_locked?.should == false
+    end
+  end
+end
diff --git a/spec/ruby/library/net/http/HTTPClientExcepton_spec.rb b/spec/ruby/library/net/http/HTTPClientExcepton_spec.rb
index 08347464ec..d576349a57 100644
--- a/spec/ruby/library/net/http/HTTPClientExcepton_spec.rb
+++ b/spec/ruby/library/net/http/HTTPClientExcepton_spec.rb
@@ -1,14 +1,12 @@
 require_relative '../../../spec_helper'
 require 'net/http'
 
-ruby_version_is "2.6" do
-  describe "Net::HTTPClientException" do
-    it "is a subclass of Net::ProtoServerError" do
-      Net::HTTPClientException.should < Net::ProtoServerError
-    end
+describe "Net::HTTPClientException" do
+  it "is a subclass of Net::ProtoServerError" do
+    Net::HTTPClientException.should < Net::ProtoServerError
+  end
 
-    it "includes the Net::HTTPExceptions module" do
-      Net::HTTPClientException.should < Net::HTTPExceptions
-    end
+  it "includes the Net::HTTPExceptions module" do
+    Net::HTTPClientException.should < Net::HTTPExceptions
   end
 end
diff --git a/spec/ruby/library/net/http/HTTPServerException_spec.rb b/spec/ruby/library/net/http/HTTPServerException_spec.rb
index 87841ab499..23b0657364 100644
--- a/spec/ruby/library/net/http/HTTPServerException_spec.rb
+++ b/spec/ruby/library/net/http/HTTPServerException_spec.rb
@@ -1,26 +1,12 @@
 require_relative '../../../spec_helper'
 require 'net/http'
 
-ruby_version_is ""..."2.6" do
-  describe "Net::HTTPServerException" do
-    it "is a subclass of Net::ProtoServerError" do
-      Net::HTTPServerException.should < Net::ProtoServerError
-    end
-
-    it "includes the Net::HTTPExceptions module" do
-      Net::HTTPServerException.should < Net::HTTPExceptions
-    end
+describe "Net::HTTPServerException" do
+  it "is a subclass of Net::ProtoServerError and is warned as deprecated" do
+    -> { Net::HTTPServerException.should < Net::ProtoServerError }.should complain(/warning: constant Net::HTTPServerException is deprecated/)
   end
-end
-
-ruby_version_is "2.6" do
-  describe "Net::HTTPServerException" do
-    it "is a subclass of Net::ProtoServerError and is warned as deprecated" do
-      -> { Net::HTTPServerException.should < Net::ProtoServerError }.should complain(/warning: constant Net::HTTPServerException is deprecated/)
-    end
 
-    it "includes the Net::HTTPExceptions module and is warned as deprecated" do
-      -> { Net::HTTPServerException.should < Net::HTTPExceptions }.should complain(/warning: constant Net::HTTPServerException is deprecated/)
-    end
+  it "includes the Net::HTTPExceptions module and is warned as deprecated" do
+    -> { Net::HTTPServerException.should < Net::HTTPExceptions }.should complain(/warning: constant Net::HTTPServerException is deprecated/)
   end
 end
diff --git a/spec/ruby/library/net/http/http/fixtures/http_server.rb b/spec/ruby/library/net/http/http/fixtures/http_server.rb
index a84e0d47d0..c06012cc86 100644
--- a/spec/ruby/library/net/http/http/fixtures/http_server.rb
+++ b/spec/ruby/library/net/http/http/fixtures/http_server.rb
@@ -63,8 +63,9 @@ module NetHTTPSpecs
     end
 
     def start_server
+      bind_address = platform_is(:windows) ? "localhost" : "127.0.0.1"
       server_config = {
-        BindAddress: "localhost",
+        BindAddress: bind_address,
         Port: 0,
         Logger: WEBrick::Log.new(NullWriter.new),
         AccessLog: [],
diff --git a/spec/ruby/library/net/http/httpresponse/error_spec.rb b/spec/ruby/library/net/http/httpresponse/error_spec.rb
index d2b2f53d89..89f4a47f60 100644
--- a/spec/ruby/library/net/http/httpresponse/error_spec.rb
+++ b/spec/ruby/library/net/http/httpresponse/error_spec.rb
@@ -16,12 +16,7 @@ describe "Net::HTTPResponse#error!" do
     -> { res.error! }.should raise_error(Net::HTTPRetriableError)
 
     res = Net::HTTPClientError.new("1.0", "4xx", "test response")
-    ruby_version_is ""..."2.6" do
-      -> { res.error! }.should raise_error(Net::HTTPServerException)
-    end
-    ruby_version_is "2.6" do
-      -> { res.error! }.should raise_error(Net::HTTPClientException)
-    end
+    -> { res.error! }.should raise_error(Net::HTTPClientException)
 
     res = Net::HTTPServerError.new("1.0", "5xx", "test response")
     -> { res.error! }.should raise_error(Net::HTTPFatalError)
diff --git a/spec/ruby/library/net/http/httpresponse/error_type_spec.rb b/spec/ruby/library/net/http/httpresponse/error_type_spec.rb
index 6705f8b1aa..8885b7706b 100644
--- a/spec/ruby/library/net/http/httpresponse/error_type_spec.rb
+++ b/spec/ruby/library/net/http/httpresponse/error_type_spec.rb
@@ -16,12 +16,7 @@ describe "Net::HTTPResponse#error_type" do
     res.error_type.should == Net::HTTPRetriableError
 
     res = Net::HTTPClientError.new("1.0", "4xx", "test response")
-    ruby_version_is ""..."2.6" do
-      res.error_type.should == Net::HTTPServerException
-    end
-    ruby_version_is "2.6" do
-      res.error_type.should == Net::HTTPClientException
-    end
+    res.error_type.should == Net::HTTPClientException
 
     res = Net::HTTPServerError.new("1.0", "5xx", "test response")
     res.error_type.should == Net::HTTPFatalError
diff --git a/spec/ruby/library/net/http/httpresponse/exception_type_spec.rb b/spec/ruby/library/net/http/httpresponse/exception_type_spec.rb
index c0812cd322..0c9c11291f 100644
--- a/spec/ruby/library/net/http/httpresponse/exception_type_spec.rb
+++ b/spec/ruby/library/net/http/httpresponse/exception_type_spec.rb
@@ -7,12 +7,7 @@ describe "Net::HTTPResponse.exception_type" do
     Net::HTTPInformation.exception_type.should == Net::HTTPError
     Net::HTTPSuccess.exception_type.should == Net::HTTPError
     Net::HTTPRedirection.exception_type.should == Net::HTTPRetriableError
-    ruby_version_is ""..."2.6" do
-      Net::HTTPClientError.exception_type.should == Net::HTTPServerException
-    end
-    ruby_version_is "2.6" do
-      Net::HTTPClientError.exception_type.should == Net::HTTPClientException
-    end
+    Net::HTTPClientError.exception_type.should == Net::HTTPClientException
     Net::HTTPServerError.exception_type.should == Net::HTTPFatalError
   end
 end
diff --git a/spec/ruby/library/net/http/httpresponse/value_spec.rb b/spec/ruby/library/net/http/httpresponse/value_spec.rb
index 4a5930d4e5..5cd58316ef 100644
--- a/spec/ruby/library/net/http/httpresponse/value_spec.rb
+++ b/spec/ruby/library/net/http/httpresponse/value_spec.rb
@@ -16,12 +16,7 @@ describe "Net::HTTPResponse#value" do
     -> { res.value }.should raise_error(Net::HTTPRetriableError)
 
     res = Net::HTTPClientError.new("1.0", "4xx", "test response")
-    ruby_version_is ""..."2.6" do
-      -> { res.value }.should raise_error(Net::HTTPServerException)
-    end
-    ruby_version_is "2.6" do
-      -> { res.value }.should raise_error(Net::HTTPClientException)
-    end
+    -> { res.value }.should raise_error(Net::HTTPClientException)
 
     res = Net::HTTPServerError.new("1.0", "5xx", "test response")
     -> { res.value }.should raise_error(Net::HTTPFatalError)
diff --git a/spec/ruby/library/objectspace/memsize_of_all_spec.rb b/spec/ruby/library/objectspace/memsize_of_all_spec.rb
new file mode 100644
index 0000000000..6898862e8f
--- /dev/null
+++ b/spec/ruby/library/objectspace/memsize_of_all_spec.rb
@@ -0,0 +1,21 @@
+require_relative '../../spec_helper'
+require 'objspace'
+
+describe "ObjectSpace.memsize_of_all" do
+  it "returns a non-zero Integer for all objects" do
+    ObjectSpace.memsize_of_all.should be_kind_of(Integer)
+    ObjectSpace.memsize_of_all.should > 0
+  end
+
+  it "returns a non-zero Integer for Class" do
+    ObjectSpace.memsize_of_all(Class).should be_kind_of(Integer)
+    ObjectSpace.memsize_of_all(Class).should > 0
+  end
+
+  it "increases when a new object is allocated" do
+    before = ObjectSpace.memsize_of_all(Class)
+    o = Class.new
+    after = ObjectSpace.memsize_of_all(Class)
+    after.should > before
+  end
+end
diff --git a/spec/ruby/library/objectspace/memsize_of_spec.rb b/spec/ruby/library/objectspace/memsize_of_spec.rb
index 36d845824d..eefafbb334 100644
--- a/spec/ruby/library/objectspace/memsize_of_spec.rb
+++ b/spec/ruby/library/objectspace/memsize_of_spec.rb
@@ -16,7 +16,7 @@ describe "ObjectSpace.memsize_of" do
     ObjectSpace.memsize_of(:abc).should == 0
   end
 
-  it "returns an Integer for an Object" do
+  it "returns a positive Integer for an Object" do
     obj = Object.new
     ObjectSpace.memsize_of(obj).should be_kind_of(Integer)
     ObjectSpace.memsize_of(obj).should > 0
diff --git a/spec/ruby/library/objectspace/trace_object_allocations_spec.rb b/spec/ruby/library/objectspace/trace_object_allocations_spec.rb
new file mode 100644
index 0000000000..3100511dc9
--- /dev/null
+++ b/spec/ruby/library/objectspace/trace_object_allocations_spec.rb
@@ -0,0 +1,131 @@
+require_relative '../../spec_helper'
+require 'objspace'
+
+describe "ObjectSpace.trace_object_allocations" do
+  it "runs a block" do
+    ScratchPad.clear
+    ObjectSpace.trace_object_allocations do
+      ScratchPad.record :a
+    end
+    ScratchPad.recorded.should == :a
+  end
+
+  it "records info for allocation_class_path" do
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+      ObjectSpace.allocation_class_path(o).should == "Class"
+      a = [1, 2, 3]
+      ObjectSpace.allocation_class_path(a).should == nil
+    end
+  end
+
+  it "records info for allocation_generation" do
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+      ObjectSpace.allocation_generation(o).should.kind_of?(Integer)
+      a = [1, 2, 3]
+      ObjectSpace.allocation_generation(a).should.kind_of?(Integer)
+    end
+  end
+
+  it "records info for allocation_method_id" do
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+      ObjectSpace.allocation_method_id(o).should == :new
+      a = [1, 2, 3]
+      ObjectSpace.allocation_method_id(a).should == nil
+    end
+  end
+
+  it "records info for allocation_sourcefile" do
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+      ObjectSpace.allocation_sourcefile(o).should == __FILE__
+      a = [1, 2, 3]
+      ObjectSpace.allocation_sourcefile(a).should == __FILE__
+    end
+  end
+
+  it "records info for allocation_sourceline" do
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+      ObjectSpace.allocation_sourceline(o).should == __LINE__ - 1
+      a = [1, 2, 3]
+      ObjectSpace.allocation_sourceline(a).should == __LINE__ - 1
+    end
+  end
+
+  it "can be cleared using trace_object_allocations_clear" do
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+      ObjectSpace.allocation_class_path(o).should == "Class"
+      ObjectSpace.trace_object_allocations_clear
+      ObjectSpace.allocation_class_path(o).should be_nil
+    end
+  end
+
+  it "does not clears allocation data after returning" do
+    o = nil
+    ObjectSpace.trace_object_allocations do
+      o = Object.new
+    end
+    ObjectSpace.allocation_class_path(o).should == "Class"
+  end
+
+  it "can be used without a block using trace_object_allocations_start and _stop" do
+    ObjectSpace.trace_object_allocations_start
+    begin
+      o = Object.new
+      ObjectSpace.allocation_class_path(o).should == "Class"
+      a = [1, 2, 3]
+      ObjectSpace.allocation_class_path(a).should == nil
+    ensure
+      ObjectSpace.trace_object_allocations_stop
+    end
+  end
+
+  it "does not clears allocation data after trace_object_allocations_stop" do
+    ObjectSpace.trace_object_allocations_start
+    begin
+      o = Object.new
+    ensure
+      ObjectSpace.trace_object_allocations_stop
+    end
+    ObjectSpace.allocation_class_path(o).should == "Class"
+  end
+
+  it "can be nested" do
+    ObjectSpace.trace_object_allocations do
+      ObjectSpace.trace_object_allocations do
+        o = Object.new
+        ObjectSpace.allocation_class_path(o).should == "Class"
+      end
+    end
+  end
+
+  it "can be nested without a block using trace_object_allocations_start and _stop" do
+    ObjectSpace.trace_object_allocations_start
+    begin
+      ObjectSpace.trace_object_allocations_start
+      begin
+        o = Object.new
+        ObjectSpace.allocation_class_path(o).should == "Class"
+      ensure
+        ObjectSpace.trace_object_allocations_stop
+      end
+    ensure
+      ObjectSpace.trace_object_allocations_stop
+    end
+  end
+
+  it "can be nested with more _stop than _start" do
+    ObjectSpace.trace_object_allocations_start
+    begin
+      o = Object.new
+      ObjectSpace.allocation_class_path(o).should == "Class"
+      ObjectSpace.trace_object_allocations_stop
+    ensure
+      ObjectSpace.trace_object_allocations_stop
+    end
+  end
+end
diff --git a/spec/ruby/library/openstruct/to_h_spec.rb b/spec/ruby/library/openstruct/to_h_spec.rb
index ebdec16174..6c272bcc71 100644
--- a/spec/ruby/library/openstruct/to_h_spec.rb
+++ b/spec/ruby/library/openstruct/to_h_spec.rb
@@ -27,44 +27,42 @@ describe "OpenStruct#to_h" do
     @os.age.should == 70
   end
 
-  ruby_version_is "2.6" do
-    context "with block" do
-      it "converts [key, value] pairs returned by the block to a hash" do
-        h = @os.to_h { |k, v| [k.to_s, v*2] }
-        h.should == { "name" => "John SmithJohn Smith", "age" => 140, "pension" => 600 }
-      end
+  context "with block" do
+    it "converts [key, value] pairs returned by the block to a hash" do
+      h = @os.to_h { |k, v| [k.to_s, v*2] }
+      h.should == { "name" => "John SmithJohn Smith", "age" => 140, "pension" => 600 }
+    end
 
-      it "raises ArgumentError if block returns longer or shorter array" do
-        -> do
-          @os.to_h { |k, v| [k.to_s, v*2, 1] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        @os.to_h { |k, v| [k.to_s, v*2, 1] }
+      end.should raise_error(ArgumentError, /element has wrong array length/)
 
-        -> do
-          @os.to_h { |k, v| [k] }
-        end.should raise_error(ArgumentError, /element has wrong array length/)
-      end
+      -> do
+        @os.to_h { |k, v| [k] }
+      end.should raise_error(ArgumentError, /element has wrong array length/)
+    end
 
-      it "raises TypeError if block returns something other than Array" do
-        -> do
-          @os.to_h { |k, v| "not-array" }
-        end.should raise_error(TypeError, /wrong element type String/)
-      end
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        @os.to_h { |k, v| "not-array" }
+      end.should raise_error(TypeError, /wrong element type String/)
+    end
 
-      it "coerces returned pair to Array with #to_ary" do
-        x = mock('x')
-        x.stub!(:to_ary).and_return([:b, 'b'])
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
 
-        @os.to_h { |k| x }.should == { :b => 'b' }
-      end
+      @os.to_h { |k| x }.should == { :b => 'b' }
+    end
 
-      it "does not coerce returned pair to Array with #to_a" do
-        x = mock('x')
-        x.stub!(:to_a).and_return([:b, 'b'])
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
 
-        -> do
-          @os.to_h { |k| x }
-        end.should raise_error(TypeError, /wrong element type MockObject/)
-      end
+      -> do
+        @os.to_h { |k| x }
+      end.should raise_error(TypeError, /wrong element type MockObject/)
     end
   end
 end
diff --git a/spec/ruby/library/rbconfig/unicode_version_spec.rb b/spec/ruby/library/rbconfig/unicode_version_spec.rb
index a6dc6478ff..fe19b10293 100644
--- a/spec/ruby/library/rbconfig/unicode_version_spec.rb
+++ b/spec/ruby/library/rbconfig/unicode_version_spec.rb
@@ -2,12 +2,6 @@ require_relative '../../spec_helper'
 require 'rbconfig'
 
 describe "RbConfig::CONFIG['UNICODE_VERSION']" do
-  ruby_version_is "2.5"..."2.6" do
-    it "is 10.0.0 for Ruby 2.5" do
-      RbConfig::CONFIG['UNICODE_VERSION'].should == "10.0.0"
-    end
-  end
-
   ruby_version_is "2.6"..."2.6.2" do
     it "is 11.0.0 for Ruby 2.6.0 and 2.6.1" do
       RbConfig::CONFIG['UNICODE_VERSION'].should == "11.0.0"
diff --git a/spec/ruby/library/set/filter_spec.rb b/spec/ruby/library/set/filter_spec.rb
index a4dfe70d52..779254ad68 100644
--- a/spec/ruby/library/set/filter_spec.rb
+++ b/spec/ruby/library/set/filter_spec.rb
@@ -1,8 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'shared/select'
 
-ruby_version_is "2.6" do
-  describe "Set#filter!" do
-    it_behaves_like :set_select_bang, :filter!
-  end
+describe "Set#filter!" do
+  it_behaves_like :set_select_bang, :filter!
 end
diff --git a/spec/ruby/library/set/sortedset/filter_spec.rb b/spec/ruby/library/set/sortedset/filter_spec.rb
index c6d881de67..3b9dcb63c9 100644
--- a/spec/ruby/library/set/sortedset/filter_spec.rb
+++ b/spec/ruby/library/set/sortedset/filter_spec.rb
@@ -4,9 +4,7 @@ ruby_version_is ""..."3.0" do
   require_relative 'shared/select'
   require 'set'
 
-  ruby_version_is "2.6" do
-    describe "SortedSet#filter!" do
-      it_behaves_like :sorted_set_select_bang, :filter!
-    end
+  describe "SortedSet#filter!" do
+    it_behaves_like :sorted_set_select_bang, :filter!
   end
 end
diff --git a/spec/ruby/library/socket/basicsocket/recv_nonblock_spec.rb b/spec/ruby/library/socket/basicsocket/recv_nonblock_spec.rb
index 0363f2f8de..b6ab8a9cea 100644
--- a/spec/ruby/library/socket/basicsocket/recv_nonblock_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/recv_nonblock_spec.rb
@@ -67,4 +67,25 @@ describe "Socket::BasicSocket#recv_nonblock" do
       }.should raise_error(IO::WaitReadable)
     end
   end
+
+  SocketSpecs.each_ip_protocol do |family, ip_address|
+    describe 'using a connected but not bound socket' do
+      before do
+        @server = Socket.new(family, :STREAM)
+      end
+
+      after do
+        @server.close
+      end
+
+      it "raises Errno::ENOTCONN" do
+        -> { @server.recv_nonblock(1) }.should raise_error { |e|
+          [Errno::ENOTCONN, Errno::EINVAL].should.include?(e.class)
+        }
+        -> { @server.recv_nonblock(1, exception: false) }.should raise_error { |e|
+          [Errno::ENOTCONN, Errno::EINVAL].should.include?(e.class)
+        }
+      end
+    end
+  end
 end
diff --git a/spec/ruby/library/socket/basicsocket/recvmsg_nonblock_spec.rb b/spec/ruby/library/socket/basicsocket/recvmsg_nonblock_spec.rb
index 8e6c232c59..cc4275c417 100644
--- a/spec/ruby/library/socket/basicsocket/recvmsg_nonblock_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/recvmsg_nonblock_spec.rb
@@ -114,6 +114,21 @@ describe 'BasicSocket#recvmsg_nonblock' do
     end
 
     platform_is_not :windows do
+      describe 'using a connected but not bound socket' do
+        before do
+          @server = Socket.new(family, :STREAM)
+        end
+
+        after do
+          @server.close
+        end
+
+        it "raises Errno::ENOTCONN" do
+          -> { @server.recvmsg_nonblock }.should raise_error(Errno::ENOTCONN)
+          -> { @server.recvmsg_nonblock(exception: false) }.should raise_error(Errno::ENOTCONN)
+        end
+      end
+
       describe 'using a connected socket' do
         before do
           @client = Socket.new(family, :STREAM)
diff --git a/spec/ruby/library/socket/basicsocket/sendmsg_nonblock_spec.rb b/spec/ruby/library/socket/basicsocket/sendmsg_nonblock_spec.rb
index c112f2ab4a..7acfc659bd 100644
--- a/spec/ruby/library/socket/basicsocket/sendmsg_nonblock_spec.rb
+++ b/spec/ruby/library/socket/basicsocket/sendmsg_nonblock_spec.rb
@@ -18,7 +18,12 @@ describe 'BasicSocket#sendmsg_nonblock' do
 
       describe 'without a destination address' do
         it "raises #{SocketSpecs.dest_addr_req_error}" do
-          -> { @client.sendmsg_nonblock('hello') }.should raise_error(SocketSpecs.dest_addr_req_error)
+          -> {
+            @client.sendmsg_nonblock('hello')
+          }.should raise_error(SocketSpecs.dest_addr_req_error)
+          -> {
+            @client.sendmsg_nonblock('hello', exception: false)
+          }.should raise_error(SocketSpecs.dest_addr_req_error)
         end
       end
 
diff --git a/spec/ruby/library/socket/socket/accept_nonblock_spec.rb b/spec/ruby/library/socket/socket/accept_nonblock_spec.rb
index 3221f0b128..011622988c 100644
--- a/spec/ruby/library/socket/socket/accept_nonblock_spec.rb
+++ b/spec/ruby/library/socket/socket/accept_nonblock_spec.rb
@@ -46,6 +46,7 @@ describe 'Socket#accept_nonblock' do
     describe 'using an unbound socket' do
       it 'raises Errno::EINVAL' do
         -> { @server.accept_nonblock }.should raise_error(Errno::EINVAL)
+        -> { @server.accept_nonblock(exception: false) }.should raise_error(Errno::EINVAL)
       end
     end
 
@@ -56,6 +57,7 @@ describe 'Socket#accept_nonblock' do
 
       it 'raises Errno::EINVAL' do
         -> { @server.accept_nonblock }.should raise_error(Errno::EINVAL)
+        -> { @server.accept_nonblock(exception: false) }.should raise_error(Errno::EINVAL)
       end
     end
 
@@ -64,6 +66,7 @@ describe 'Socket#accept_nonblock' do
         @server.close
 
         -> { @server.accept_nonblock }.should raise_error(IOError)
+        -> { @server.accept_nonblock(exception: false) }.should raise_error(IOError)
       end
     end
 
diff --git a/spec/ruby/optional/capi/debug_spec.rb b/spec/ruby/optional/capi/debug_spec.rb
index 89e72f0049..c8c91417d1 100644
--- a/spec/ruby/optional/capi/debug_spec.rb
+++ b/spec/ruby/optional/capi/debug_spec.rb
@@ -34,13 +34,11 @@ describe "C-API Debug function" do
       b.local_variable_get(:a).should == "test"
     end
 
-    ruby_version_is "2.6" do
-      it "matches the locations in rb_debug_inspector_backtrace_locations" do
-        frames = @o.rb_debug_inspector_open(42);
-        frames.each do |_s, _klass, binding, _iseq, backtrace_location|
-          if binding
-            "#{backtrace_location.path}:#{backtrace_location.lineno}".should == "#{binding.source_location[0]}:#{binding.source_location[1]}"
-          end
+    it "matches the locations in rb_debug_inspector_backtrace_locations" do
+      frames = @o.rb_debug_inspector_open(42);
+      frames.each do |_s, _klass, binding, _iseq, backtrace_location|
+        if binding
+          "#{backtrace_location.path}:#{backtrace_location.lineno}".should == "#{binding.source_location[0]}:#{binding.source_location[1]}"
         end
       end
     end
diff --git a/spec/ruby/optional/capi/encoding_spec.rb b/spec/ruby/optional/capi/encoding_spec.rb
index 93bde54069..66c2dd40de 100644
--- a/spec/ruby/optional/capi/encoding_spec.rb
+++ b/spec/ruby/optional/capi/encoding_spec.rb
@@ -31,13 +31,11 @@ describe :rb_enc_set_index, shared: true do
     result.first.should == result.last
   end
 
-  ruby_version_is "2.6" do
-    it "raises an ArgumentError for a non-encoding capable object" do
-      obj = Object.new
-      -> {
-        result = @s.send(@method, obj, 1)
-      }.should raise_error(ArgumentError, "cannot set encoding on non-encoding capable object")
-    end
+  it "raises an ArgumentError for a non-encoding capable object" do
+    obj = Object.new
+    -> {
+      result = @s.send(@method, obj, 1)
+    }.should raise_error(ArgumentError, "cannot set encoding on non-encoding capable object")
   end
 end
 
@@ -48,13 +46,11 @@ describe "C-API Encoding function" do
     @s = CApiEncodingSpecs.new
   end
 
-  ruby_version_is "2.6" do
-    describe "rb_enc_alias" do
-      it "creates an alias for an existing Encoding" do
-        name = "ZOMGWTFBBQ#{@n += 1}"
-        @s.rb_enc_alias(name, "UTF-8").should >= 0
-        Encoding.find(name).name.should == "UTF-8"
-      end
+  describe "rb_enc_alias" do
+    it "creates an alias for an existing Encoding" do
+      name = "ZOMGWTFBBQ#{@n += 1}"
+      @s.rb_enc_alias(name, "UTF-8").should >= 0
+      Encoding.find(name).name.should == "UTF-8"
     end
   end
 
@@ -239,11 +235,9 @@ describe "C-API Encoding function" do
       @s.rb_enc_get_index(1).should == -1
     end
 
-    ruby_version_is "2.6" do
-      it "returns -1 for an object without an encoding" do
-        obj = Object.new
-        @s.rb_enc_get_index(obj).should == -1
-      end
+    it "returns -1 for an object without an encoding" do
+      obj = Object.new
+      @s.rb_enc_get_index(obj).should == -1
     end
   end
 
diff --git a/spec/ruby/optional/capi/ext/fiber_spec.c b/spec/ruby/optional/capi/ext/fiber_spec.c
new file mode 100644
index 0000000000..7912e878f3
--- /dev/null
+++ b/spec/ruby/optional/capi/ext/fiber_spec.c
@@ -0,0 +1,58 @@
+#include "ruby.h"
+#include "rubyspec.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+VALUE fiber_spec_rb_fiber_current(VALUE self) {
+  return rb_fiber_current();
+}
+
+VALUE fiber_spec_rb_fiber_alive_p(VALUE self, VALUE fiber) {
+  return rb_fiber_alive_p(fiber);
+}
+
+VALUE fiber_spec_rb_fiber_resume(VALUE self, VALUE fiber, VALUE ary) {
+    long argc = RARRAY_LEN(ary);
+    VALUE *argv = (VALUE*) alloca(sizeof(VALUE) * argc);
+    int i;
+
+    for (i = 0; i < argc; i++) {
+      argv[i] = rb_ary_entry(ary, i);
+    }
+
+  return rb_fiber_resume(fiber, (int)argc, argv);
+}
+
+VALUE fiber_spec_rb_fiber_yield(VALUE self, VALUE ary) {
+  long argc = RARRAY_LEN(ary);
+  VALUE *argv = (VALUE*) alloca(sizeof(VALUE) * argc);
+  int i;
+
+  for (i = 0; i < argc; i++) {
+    argv[i] = rb_ary_entry(ary, i);
+  }
+  return rb_fiber_yield((int)argc, argv);
+}
+
+VALUE fiber_spec_rb_fiber_new_function(RB_BLOCK_CALL_FUNC_ARGLIST(args, dummy)) {
+  return rb_funcall(args, rb_intern("inspect"), 0);
+}
+
+VALUE fiber_spec_rb_fiber_new(VALUE self) {
+  return rb_fiber_new(fiber_spec_rb_fiber_new_function, Qnil);
+}
+
+void Init_fiber_spec(void) {
+  VALUE cls = rb_define_class("CApiFiberSpecs", rb_cObject);
+  rb_define_method(cls, "rb_fiber_current", fiber_spec_rb_fiber_current, 0);
+  rb_define_method(cls, "rb_fiber_alive_p", fiber_spec_rb_fiber_alive_p, 1);
+  rb_define_method(cls, "rb_fiber_resume", fiber_spec_rb_fiber_resume, 2);
+  rb_define_method(cls, "rb_fiber_yield", fiber_spec_rb_fiber_yield, 1);
+  rb_define_method(cls, "rb_fiber_new", fiber_spec_rb_fiber_new, 0);
+}
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/spec/ruby/optional/capi/ext/regexp_spec.c b/spec/ruby/optional/capi/ext/regexp_spec.c
index 70780bae2a..0a62616f33 100644
--- a/spec/ruby/optional/capi/ext/regexp_spec.c
+++ b/spec/ruby/optional/capi/ext/regexp_spec.c
@@ -35,6 +35,11 @@ VALUE regexp_spec_backref_get(VALUE self) {
   return rb_backref_get();
 }
 
+static VALUE regexp_spec_backref_set(VALUE self, VALUE backref) {
+  rb_backref_set(backref);
+  return Qnil;
+}
+
 VALUE regexp_spec_reg_match_backref_get(VALUE self, VALUE re, VALUE str) {
   rb_reg_match(re, str);
   return rb_backref_get();
@@ -51,6 +56,7 @@ void Init_regexp_spec(void) {
   rb_define_method(cls, "a_re_1st_match", regexp_spec_reg_1st_match, 1);
   rb_define_method(cls, "rb_reg_match", regexp_spec_reg_match, 2);
   rb_define_method(cls, "rb_backref_get", regexp_spec_backref_get, 0);
+  rb_define_method(cls, "rb_backref_set", regexp_spec_backref_set, 1);
   rb_define_method(cls, "rb_reg_match_backref_get", regexp_spec_reg_match_backref_get, 2);
   rb_define_method(cls, "rb_reg_options", regexp_spec_rb_reg_options, 1);
   rb_define_method(cls, "rb_reg_regcomp", regexp_spec_rb_reg_regcomp, 1);
diff --git a/spec/ruby/optional/capi/ext/rubyspec.h b/spec/ruby/optional/capi/ext/rubyspec.h
index a10ab49f7c..7e4a252b38 100644
--- a/spec/ruby/optional/capi/ext/rubyspec.h
+++ b/spec/ruby/optional/capi/ext/rubyspec.h
@@ -55,6 +55,7 @@
 #define rb_catch(tag, func, data) rb_catch(tag, RUBY_METHOD_FUNC(func), data)
 #define rb_catch_obj(tag, func, data) rb_catch_obj(tag, RUBY_METHOD_FUNC(func), data)
 #define rb_proc_new(fn, arg) rb_proc_new(RUBY_METHOD_FUNC(fn), arg)
+#define rb_fiber_new(fn, arg) rb_fiber_new(RUBY_METHOD_FUNC(fn), arg)
 #define rb_thread_create(fn, arg) rb_thread_create(RUBY_METHOD_FUNC(fn), arg)
 #define rb_define_hooked_variable(name, var, getter, setter) rb_define_hooked_variable(name, var, RUBY_METHOD_FUNC(getter), (void (*)(...))setter)
 #endif
diff --git a/spec/ruby/optional/capi/ext/string_spec.c b/spec/ruby/optional/capi/ext/string_spec.c
index dd7bc397cd..f2245be0ef 100644
--- a/spec/ruby/optional/capi/ext/string_spec.c
+++ b/spec/ruby/optional/capi/ext/string_spec.c
@@ -1,6 +1,7 @@
 #include "ruby.h"
 #include "rubyspec.h"
 
+#include <fcntl.h>
 #include <string.h>
 #include <stdarg.h>
 
@@ -279,6 +280,16 @@ VALUE string_spec_rb_str_resize_RSTRING_LEN(VALUE self, VALUE str, VALUE size) {
   return INT2FIX(RSTRING_LEN(modified));
 }
 
+VALUE string_spec_rb_str_resize_copy(VALUE self, VALUE str) {
+  rb_str_modify_expand(str, 5);
+  char *buffer = RSTRING_PTR(str);
+  buffer[1] = 'e';
+  buffer[2] = 's';
+  buffer[3] = 't';
+  rb_str_resize(str, 4);
+  return str;
+}
+
 VALUE string_spec_rb_str_split(VALUE self, VALUE str) {
   return rb_str_split(str, ",");
 }
@@ -374,6 +385,20 @@ VALUE string_spec_RSTRING_PTR_after_yield(VALUE self, VALUE str) {
   return from_rstring_ptr;
 }
 
+VALUE string_spec_RSTRING_PTR_read(VALUE self, VALUE str, VALUE path) {
+  char *cpath = StringValueCStr(path);
+  int fd = open(cpath, O_RDONLY);
+  rb_str_modify_expand(str, 10);
+  char *buffer = RSTRING_PTR(str);
+  read(fd, buffer, 10);
+  rb_str_modify_expand(str, 21);
+  char *buffer2 = RSTRING_PTR(str);
+  read(fd, buffer2 + 10, 11);
+  rb_str_set_len(str, 21);
+  close(fd);
+  return str;
+}
+
 VALUE string_spec_StringValue(VALUE self, VALUE str) {
   return StringValue(str);
 }
@@ -476,6 +501,18 @@ static VALUE string_spec_rb_utf8_str_new_cstr(VALUE self) {
   return rb_utf8_str_new_cstr("nokogiri");
 }
 
+static VALUE call_rb_str_vcatf(VALUE mesg, const char *fmt, ...){
+  va_list ap;
+  va_start(ap, fmt);
+  VALUE result = rb_str_vcatf(mesg, fmt, ap);
+  va_end(ap);
+  return result;
+}
+
+static VALUE string_spec_rb_str_vcatf(VALUE self, VALUE mesg) {
+  return call_rb_str_vcatf(mesg, "fmt %d %d number", 42, 7);
+}
+
 void Init_string_spec(void) {
   VALUE cls = rb_define_class("CApiStringSpecs", rb_cObject);
   rb_define_method(cls, "rb_cstr2inum", string_spec_rb_cstr2inum, 2);
@@ -527,6 +564,7 @@ void Init_string_spec(void) {
   rb_define_method(cls, "rb_str_modify_expand", string_spec_rb_str_modify_expand, 2);
   rb_define_method(cls, "rb_str_resize", string_spec_rb_str_resize, 2);
   rb_define_method(cls, "rb_str_resize_RSTRING_LEN", string_spec_rb_str_resize_RSTRING_LEN, 2);
+  rb_define_method(cls, "rb_str_resize_copy", string_spec_rb_str_resize_copy, 1);
   rb_define_method(cls, "rb_str_set_len", string_spec_rb_str_set_len, 2);
   rb_define_method(cls, "rb_str_set_len_RSTRING_LEN", string_spec_rb_str_set_len_RSTRING_LEN, 2);
   rb_define_method(cls, "rb_str_split", string_spec_rb_str_split, 1);
@@ -542,6 +580,7 @@ void Init_string_spec(void) {
   rb_define_method(cls, "RSTRING_PTR_set", string_spec_RSTRING_PTR_set, 3);
   rb_define_method(cls, "RSTRING_PTR_after_funcall", string_spec_RSTRING_PTR_after_funcall, 2);
   rb_define_method(cls, "RSTRING_PTR_after_yield", string_spec_RSTRING_PTR_after_yield, 1);
+  rb_define_method(cls, "RSTRING_PTR_read", string_spec_RSTRING_PTR_read, 2);
   rb_define_method(cls, "StringValue", string_spec_StringValue, 1);
   rb_define_method(cls, "SafeStringValue", string_spec_SafeStringValue, 1);
   rb_define_method(cls, "rb_str_hash", string_spec_rb_str_hash, 1);
@@ -563,6 +602,7 @@ void Init_string_spec(void) {
   rb_define_method(cls, "rb_utf8_str_new_static", string_spec_rb_utf8_str_new_static, 0);
   rb_define_method(cls, "rb_utf8_str_new", string_spec_rb_utf8_str_new, 0);
   rb_define_method(cls, "rb_utf8_str_new_cstr", string_spec_rb_utf8_str_new_cstr, 0);
+  rb_define_method(cls, "rb_str_vcatf", string_spec_rb_str_vcatf, 1);
 }
 
 #ifdef __cplusplus
diff --git a/spec/ruby/optional/capi/fiber_spec.rb b/spec/ruby/optional/capi/fiber_spec.rb
new file mode 100644
index 0000000000..196ddc45fb
--- /dev/null
+++ b/spec/ruby/optional/capi/fiber_spec.rb
@@ -0,0 +1,51 @@
+require_relative 'spec_helper'
+require 'fiber'
+
+load_extension('fiber')
+
+describe "C-API Fiber function" do
+  before :each do
+    @s = CApiFiberSpecs.new
+  end
+
+  describe "rb_fiber_current" do
+    it "returns the current fiber" do
+      result = @s.rb_fiber_current()
+      result.should be_an_instance_of(Fiber)
+      result.should == Fiber.current
+    end
+  end
+
+  describe "rb_fiber_alive_p" do
+    it "returns the fibers alive status" do
+      fiber = Fiber.new { Fiber.yield }
+      fiber.resume
+      @s.rb_fiber_alive_p(fiber).should be_true
+      fiber.resume
+      @s.rb_fiber_alive_p(fiber).should be_false
+    end
+  end
+
+  describe "rb_fiber_resume" do
+    it "resumes the fiber" do
+      fiber = Fiber.new { |arg| Fiber.yield arg }
+      @s.rb_fiber_resume(fiber, [1]).should == 1
+      @s.rb_fiber_resume(fiber, [2]).should == 2
+    end
+  end
+
+  describe "rb_fiber_yield" do
+    it "yields the fiber" do
+      fiber = Fiber.new { @s.rb_fiber_yield([1]) }
+      fiber.resume.should == 1
+    end
+  end
+
+  describe "rb_fiber_new" do
+    it "returns a new fiber" do
+      fiber = @s.rb_fiber_new
+      fiber.should be_an_instance_of(Fiber)
+      fiber.resume(42).should == "42"
+    end
+  end
+end
diff --git a/spec/ruby/optional/capi/fixtures/read.txt b/spec/ruby/optional/capi/fixtures/read.txt
new file mode 100644
index 0000000000..f976cfd9b9
--- /dev/null
+++ b/spec/ruby/optional/capi/fixtures/read.txt
@@ -0,0 +1 @@
+fixture file contents
diff --git a/spec/ruby/optional/capi/proc_spec.rb b/spec/ruby/optional/capi/proc_spec.rb
index ff119416f6..6e797fdeb4 100644
--- a/spec/ruby/optional/capi/proc_spec.rb
+++ b/spec/ruby/optional/capi/proc_spec.rb
@@ -104,8 +104,9 @@ describe "C-API when calling Proc.new from a C function" do
 
   # Ruby -> C -> Ruby -> Proc.new
   it "raises an ArgumentError when the C function calls a Ruby method that calls Proc.new" do
-    def @p.Proc_new() Proc.new end
-    -> { @p.rb_Proc_new(2) { :called } }.should raise_error(ArgumentError)
+    -> {
+      @p.rb_Proc_new(2) { :called }
+    }.should raise_error(ArgumentError)
   end
 
   # Ruby -> C -> Ruby -> C -> rb_funcall(Proc.new)
diff --git a/spec/ruby/optional/capi/regexp_spec.rb b/spec/ruby/optional/capi/regexp_spec.rb
index 806157368d..81844e2a6e 100644
--- a/spec/ruby/optional/capi/regexp_spec.rb
+++ b/spec/ruby/optional/capi/regexp_spec.rb
@@ -80,4 +80,33 @@ describe "C-API Regexp function" do
        @p.rb_reg_match_backref_get(/a/, 'ab')[0].should == 'a'
     end
   end
+
+  describe "rb_backref_set" do
+    before :each do
+      @md = "foo".match(/foo/)
+      $~ = nil
+    end
+
+    it "sets the value of $~" do
+      @p.rb_backref_set(@md)
+      @p.rb_backref_get.should == @md
+      $~.should == @md
+    end
+
+    it "sets a Thread-local value" do
+      running = false
+
+      thr = Thread.new do
+        @p.rb_backref_set(@md)
+        @p.rb_backref_get.should == @md
+        $~.should == @md
+        running = true
+      end
+
+      Thread.pass while thr.status and !running
+      $~.should be_nil
+
+      thr.join
+    end
+  end
 end
diff --git a/spec/ruby/optional/capi/string_spec.rb b/spec/ruby/optional/capi/string_spec.rb
index 7c33b79348..151dfefef7 100644
--- a/spec/ruby/optional/capi/string_spec.rb
+++ b/spec/ruby/optional/capi/string_spec.rb
@@ -598,6 +598,12 @@ describe "C-API String function" do
       str = "        "
       @s.RSTRING_PTR_short_memcpy(str).should == "Infinity"
     end
+
+    it "allows read to update string contents" do
+      filename = fixture(__FILE__, "read.txt")
+      str = ""
+      @s.RSTRING_PTR_read(str, filename).should == "fixture file contents"
+    end
   end
 
   describe "RSTRING_LEN" do
@@ -665,6 +671,12 @@ describe "C-API String function" do
     end
   end
 
+  describe "rb_str_modify" do
+    it "raises an error if the string is frozen" do
+      -> { @s.rb_str_modify("frozen".freeze) }.should raise_error(FrozenError)
+    end
+  end
+
   describe "rb_str_modify_expand" do
     it "grows the capacity to bytesize + expand, not changing the bytesize" do
       str = @s.rb_str_buf_new(256, "abcd")
@@ -684,6 +696,15 @@ describe "C-API String function" do
       str.bytesize.should == 3
       @s.RSTRING_LEN(str).should == 3
       @s.rb_str_capacity(str).should == 1027
+
+      @s.rb_str_modify_expand(str, 1)
+      str.bytesize.should == 3
+      @s.RSTRING_LEN(str).should == 3
+      @s.rb_str_capacity(str).should == 4
+    end
+
+    it "raises an error if the string is frozen" do
+      -> { @s.rb_str_modify_expand("frozen".freeze, 10) }.should raise_error(FrozenError)
     end
   end
 
@@ -700,6 +721,11 @@ describe "C-API String function" do
       @s.rb_str_resize_RSTRING_LEN("test", 2).should == 2
     end
 
+    it "copies the existing bytes" do
+      str = "t"
+      @s.rb_str_resize_copy(str).should == "test"
+    end
+
     it "increases the size of the string" do
       expected = "test".force_encoding("US-ASCII")
       str = @s.rb_str_resize(expected.dup, 12)
@@ -1116,4 +1142,14 @@ end
       str.encoding.should == Encoding::UTF_8
     end
   end
+
+  describe "rb_str_vcatf" do
+    it "appends the message to the string" do
+      @s.rb_str_vcatf("").should == "fmt 42 7 number"
+
+      str = "test "
+      @s.rb_str_vcatf(str)
+      str.should == "test fmt 42 7 number"
+    end
+  end
 end
diff --git a/spec/ruby/security/cve_2019_8321_spec.rb b/spec/ruby/security/cve_2019_8321_spec.rb
index affcd00e02..a8a86e7d97 100644
--- a/spec/ruby/security/cve_2019_8321_spec.rb
+++ b/spec/ruby/security/cve_2019_8321_spec.rb
@@ -3,20 +3,18 @@ require_relative '../spec_helper'
 require 'rubygems'
 require 'rubygems/user_interaction'
 
-ruby_version_is "2.5.5" do
-  describe "CVE-2019-8321 is resisted by" do
-    it "sanitising verbose messages" do
-      ui = Class.new {
-        include Gem::UserInteraction
-      }.new
-      ui.should_receive(:say).with(".]2;nyan.")
-      verbose_before = Gem.configuration.verbose
-      begin
-        Gem.configuration.verbose = :really_verbose
-        ui.verbose("\e]2;nyan\a")
-      ensure
-        Gem.configuration.verbose = verbose_before
-      end
+describe "CVE-2019-8321 is resisted by" do
+  it "sanitising verbose messages" do
+    ui = Class.new {
+      include Gem::UserInteraction
+    }.new
+    ui.should_receive(:say).with(".]2;nyan.")
+    verbose_before = Gem.configuration.verbose
+    begin
+      Gem.configuration.verbose = :really_verbose
+      ui.verbose("\e]2;nyan\a")
+    ensure
+      Gem.configuration.verbose = verbose_before
     end
   end
 end
diff --git a/spec/ruby/security/cve_2019_8322_spec.rb b/spec/ruby/security/cve_2019_8322_spec.rb
index 04fb1a7a26..b70d78c033 100644
--- a/spec/ruby/security/cve_2019_8322_spec.rb
+++ b/spec/ruby/security/cve_2019_8322_spec.rb
@@ -5,19 +5,17 @@ require 'rubygems'
 require 'rubygems/safe_yaml'
 require 'rubygems/commands/owner_command'
 
-ruby_version_is "2.5.5" do
-  describe "CVE-2019-8322 is resisted by" do
-    it "sanitising owner names" do
-      command = Gem::Commands::OwnerCommand.new
-      def command.rubygems_api_request(*args)
-        Struct.new(:body).new("---\n- email: \"\e]2;nyan\a\"\n  handle: handle\n  id: id\n")
-      end
-      def command.with_response(response)
-        yield response
-      end
-      command.should_receive(:say).with("Owners for gem: name")
-      command.should_receive(:say).with("- .]2;nyan.")
-      command.show_owners "name"
+describe "CVE-2019-8322 is resisted by" do
+  it "sanitising owner names" do
+    command = Gem::Commands::OwnerCommand.new
+    def command.rubygems_api_request(*args)
+      Struct.new(:body).new("---\n- email: \"\e]2;nyan\a\"\n  handle: handle\n  id: id\n")
     end
+    def command.with_response(response)
+      yield response
+    end
+    command.should_receive(:say).with("Owners for gem: name")
+    command.should_receive(:say).with("- .]2;nyan.")
+    command.show_owners "name"
   end
 end
diff --git a/spec/ruby/security/cve_2019_8323_spec.rb b/spec/ruby/security/cve_2019_8323_spec.rb
index af0b270880..d4606de054 100644
--- a/spec/ruby/security/cve_2019_8323_spec.rb
+++ b/spec/ruby/security/cve_2019_8323_spec.rb
@@ -5,34 +5,32 @@ require 'optparse'
 require 'rubygems'
 require 'rubygems/gemcutter_utilities'
 
-ruby_version_is "2.5.5" do
-  describe "CVE-2019-8323 is resisted by" do
-    describe "sanitising the body" do
-      it "for success codes" do
-        cutter = Class.new {
-          include Gem::GemcutterUtilities
-        }.new
-        response = Net::HTTPSuccess.new(nil, nil, nil)
-        def response.body
-          "\e]2;nyan\a"
-        end
-        cutter.should_receive(:say).with(".]2;nyan.")
-        cutter.with_response response
+describe "CVE-2019-8323 is resisted by" do
+  describe "sanitising the body" do
+    it "for success codes" do
+      cutter = Class.new {
+        include Gem::GemcutterUtilities
+      }.new
+      response = Net::HTTPSuccess.new(nil, nil, nil)
+      def response.body
+        "\e]2;nyan\a"
       end
+      cutter.should_receive(:say).with(".]2;nyan.")
+      cutter.with_response response
+    end
 
-      it "for error codes" do
-        cutter = Class.new {
-          include Gem::GemcutterUtilities
-        }.new
-        def cutter.terminate_interaction(n)
-        end
-        response = Net::HTTPNotFound.new(nil, nil, nil)
-        def response.body
-          "\e]2;nyan\a"
-        end
-        cutter.should_receive(:say).with(".]2;nyan.")
-        cutter.with_response response
+    it "for error codes" do
+      cutter = Class.new {
+        include Gem::GemcutterUtilities
+      }.new
+      def cutter.terminate_interaction(n)
+      end
+      response = Net::HTTPNotFound.new(nil, nil, nil)
+      def response.body
+        "\e]2;nyan\a"
       end
+      cutter.should_receive(:say).with(".]2;nyan.")
+      cutter.with_response response
     end
   end
 end
diff --git a/spec/ruby/security/cve_2019_8325_spec.rb b/spec/ruby/security/cve_2019_8325_spec.rb
index dcdbe34210..935f127d7f 100644
--- a/spec/ruby/security/cve_2019_8325_spec.rb
+++ b/spec/ruby/security/cve_2019_8325_spec.rb
@@ -3,7 +3,7 @@ require_relative '../spec_helper'
 require 'rubygems'
 require 'rubygems/command_manager'
 
-ruby_version_is "2.5.5" do
+platform_is_not :darwin do # frequent timeout/hang on macOS
   describe "CVE-2019-8325 is resisted by" do
     describe "sanitising error message components" do
       it "for the 'while executing' message" do
diff --git a/spec/ruby/security/cve_2020_10663_spec.rb b/spec/ruby/security/cve_2020_10663_spec.rb
index b97323af08..766590d501 100644
--- a/spec/ruby/security/cve_2020_10663_spec.rb
+++ b/spec/ruby/security/cve_2020_10663_spec.rb
@@ -18,12 +18,11 @@ module JSONSpecs
 end
 
 guard -> {
-  ruby_version_is "2.5.8"..."2.6.0" or
   ruby_version_is "2.6.6" or
   JSON.const_defined?(:Pure) or
   version_is(JSON::VERSION, '2.3.0')
 } do
-  platform_is_not :darwin do
+  platform_is_not :darwin do # frequent timeout/hang on macOS
     describe "CVE-2020-10663 is resisted by" do
       it "only creating custom objects if passed create_additions: true or using JSON.load" do
         obj = JSONSpecs::MyClass.new("bar")
diff --git a/spec/ruby/shared/rational/Rational.rb b/spec/ruby/shared/rational/Rational.rb
index 2c36243dc3..936a90c086 100644
--- a/spec/ruby/shared/rational/Rational.rb
+++ b/spec/ruby/shared/rational/Rational.rb
@@ -101,42 +101,40 @@ describe :kernel_Rational, shared: true do
     end
   end
 
-  ruby_version_is "2.6" do
-    describe "when passed exception: false" do
-      describe "and [non-Numeric]" do
-        it "swallows an error" do
-          Rational(:sym, exception: false).should == nil
-          Rational("abc", exception: false).should == nil
-        end
+  describe "when passed exception: false" do
+    describe "and [non-Numeric]" do
+      it "swallows an error" do
+        Rational(:sym, exception: false).should == nil
+        Rational("abc", exception: false).should == nil
       end
+    end
 
-      describe "and [non-Numeric, Numeric]" do
-        it "swallows an error" do
-          Rational(:sym, 1, exception: false).should == nil
-          Rational("abc", 1, exception: false).should == nil
-        end
+    describe "and [non-Numeric, Numeric]" do
+      it "swallows an error" do
+        Rational(:sym, 1, exception: false).should == nil
+        Rational("abc", 1, exception: false).should == nil
       end
+    end
 
-      describe "and [anything, non-Numeric]" do
-        it "swallows an error" do
-          Rational(:sym, :sym, exception: false).should == nil
-          Rational("abc", :sym, exception: false).should == nil
-        end
+    describe "and [anything, non-Numeric]" do
+      it "swallows an error" do
+        Rational(:sym, :sym, exception: false).should == nil
+        Rational("abc", :sym, exception: false).should == nil
       end
+    end
 
-      describe "and non-Numeric String arguments" do
-        it "swallows an error" do
-          Rational("a", "b", exception: false).should == nil
-          Rational("a", 0, exception: false).should == nil
-          Rational(0, "b", exception: false).should == nil
-        end
+    describe "and non-Numeric String arguments" do
+      it "swallows an error" do
+        Rational("a", "b", exception: false).should == nil
+        Rational("a", 0, exception: false).should == nil
+        Rational(0, "b", exception: false).should == nil
       end
+    end
 
-      describe "and nil arguments" do
-        it "swallows an error" do
-          Rational(nil, exception: false).should == nil
-          Rational(nil, nil, exception: false).should == nil
-        end
+    describe "and nil arguments" do
+      it "swallows an error" do
+        Rational(nil, exception: false).should == nil
+        Rational(nil, nil, exception: false).should == nil
       end
     end
   end