Update to ruby/spec@37e52e5

48 files changed, 812 insertions, 65 deletions

diff --git a/spec/ruby/core/array/drop_spec.rb b/spec/ruby/core/array/drop_spec.rb
index 84ea86b04c..f911fd9018 100644
--- a/spec/ruby/core/array/drop_spec.rb
+++ b/spec/ruby/core/array/drop_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "Array#drop" do
   it "removes the specified number of elements from the start of the array" do
@@ -48,4 +49,16 @@ describe "Array#drop" do
 
     -> { [1, 2].drop(obj) }.should raise_error(TypeError)
   end
+
+  ruby_version_is ''...'3.0' do
+    it 'returns a subclass instance for Array subclasses' do
+      ArraySpecs::MyArray[1, 2, 3, 4, 5].drop(1).should be_an_instance_of(ArraySpecs::MyArray)
+    end
+  end
+
+  ruby_version_is '3.0' do
+    it 'returns a Array instance for Array subclasses' do
+      ArraySpecs::MyArray[1, 2, 3, 4, 5].drop(1).should be_an_instance_of(Array)
+    end
+  end
 end
diff --git a/spec/ruby/core/array/drop_while_spec.rb b/spec/ruby/core/array/drop_while_spec.rb
index cfb6b1e267..bb783d22a5 100644
--- a/spec/ruby/core/array/drop_while_spec.rb
+++ b/spec/ruby/core/array/drop_while_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "Array#drop_while" do
   it "removes elements from the start of the array while the block evaluates to true" do
@@ -12,4 +13,16 @@ describe "Array#drop_while" do
   it "removes elements from the start of the array until the block returns false" do
     [1, 2, 3, false, 5].drop_while { |n| n }.should == [false, 5]
   end
+
+  ruby_version_is ''...'3.0' do
+    it 'returns a subclass instance for Array subclasses' do
+      ArraySpecs::MyArray[1, 2, 3, 4, 5].drop_while { |n| n < 4 }.should be_an_instance_of(ArraySpecs::MyArray)
+    end
+  end
+
+  ruby_version_is '3.0' do
+    it 'returns a Array instance for Array subclasses' do
+      ArraySpecs::MyArray[1, 2, 3, 4, 5].drop_while { |n| n < 4 }.should be_an_instance_of(Array)
+    end
+  end
 end
diff --git a/spec/ruby/core/array/slice_spec.rb b/spec/ruby/core/array/slice_spec.rb
index f416d8d0ce..2f98df9488 100644
--- a/spec/ruby/core/array/slice_spec.rb
+++ b/spec/ruby/core/array/slice_spec.rb
@@ -185,6 +185,64 @@ describe "Array#slice!" do
       a.should == [3, 4]
     end
   end
+
+  describe "with a subclass of Array" do
+    before :each do
+      @array = ArraySpecs::MyArray[1, 2, 3, 4, 5]
+    end
+
+    ruby_version_is ''...'3.0' do
+      it "returns a subclass instance with [n, m]" do
+        @array.slice!(0, 2).should be_an_instance_of(ArraySpecs::MyArray)
+      end
+
+      it "returns a subclass instance with [-n, m]" do
+        @array.slice!(-3, 2).should be_an_instance_of(ArraySpecs::MyArray)
+      end
+
+      it "returns a subclass instance with [n..m]" do
+        @array.slice!(1..3).should be_an_instance_of(ArraySpecs::MyArray)
+      end
+
+      it "returns a subclass instance with [n...m]" do
+        @array.slice!(1...3).should be_an_instance_of(ArraySpecs::MyArray)
+      end
+
+      it "returns a subclass instance with [-n..-m]" do
+        @array.slice!(-3..-1).should be_an_instance_of(ArraySpecs::MyArray)
+      end
+
+      it "returns a subclass instance with [-n...-m]" do
+        @array.slice!(-3...-1).should be_an_instance_of(ArraySpecs::MyArray)
+      end
+    end
+
+    ruby_version_is '3.0' do
+      it "returns a Array instance with [n, m]" do
+        @array.slice!(0, 2).should be_an_instance_of(Array)
+      end
+
+      it "returns a Array instance with [-n, m]" do
+        @array.slice!(-3, 2).should be_an_instance_of(Array)
+      end
+
+      it "returns a Array instance with [n..m]" do
+        @array.slice!(1..3).should be_an_instance_of(Array)
+      end
+
+      it "returns a Array instance with [n...m]" do
+        @array.slice!(1...3).should be_an_instance_of(Array)
+      end
+
+      it "returns a Array instance with [-n..-m]" do
+        @array.slice!(-3..-1).should be_an_instance_of(Array)
+      end
+
+      it "returns a Array instance with [-n...-m]" do
+        @array.slice!(-3...-1).should be_an_instance_of(Array)
+      end
+    end
+  end
 end
 
 describe "Array#slice" do
diff --git a/spec/ruby/core/array/take_spec.rb b/spec/ruby/core/array/take_spec.rb
index 0de99b0a7e..4fb6f0ce75 100644
--- a/spec/ruby/core/array/take_spec.rb
+++ b/spec/ruby/core/array/take_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "Array#take" do
   it "returns the first specified number of elements" do
@@ -24,4 +25,16 @@ describe "Array#take" do
   it "raises an ArgumentError when the argument is negative" do
     ->{ [1].take(-3) }.should raise_error(ArgumentError)
   end
+
+  ruby_version_is ''...'3.0' do
+    it 'returns a subclass instance for Array subclasses' do
+      ArraySpecs::MyArray[1, 2, 3, 4, 5].take(1).should be_an_instance_of(ArraySpecs::MyArray)
+    end
+  end
+
+  ruby_version_is '3.0' do
+    it 'returns a Array instance for Array subclasses' do
+      ArraySpecs::MyArray[1, 2, 3, 4, 5].take(1).should be_an_instance_of(Array)
+    end
+  end
 end
diff --git a/spec/ruby/core/array/take_while_spec.rb b/spec/ruby/core/array/take_while_spec.rb
index f159e6f251..363419b265 100644
--- a/spec/ruby/core/array/take_while_spec.rb
+++ b/spec/ruby/core/array/take_while_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "Array#take_while" do
   it "returns all elements until the block returns false" do
@@ -12,4 +13,16 @@ describe "Array#take_while" do
   it "returns all elements until the block returns false" do
     [1, 2, false, 4].take_while{ |element| element }.should == [1, 2]
   end
+
+  ruby_version_is ''...'3.0' do
+    it 'returns a subclass instance for Array subclasses' do
+      ArraySpecs::MyArray[1, 2, 3, 4, 5].take_while { |n| n < 4 }.should be_an_instance_of(ArraySpecs::MyArray)
+    end
+  end
+
+  ruby_version_is '3.0' do
+    it 'returns a Array instance for Array subclasses' do
+      ArraySpecs::MyArray[1, 2, 3, 4, 5].take_while { |n| n < 4 }.should be_an_instance_of(Array)
+    end
+  end
 end
diff --git a/spec/ruby/core/basicobject/singleton_method_added_spec.rb b/spec/ruby/core/basicobject/singleton_method_added_spec.rb
index 8d256e22db..ab6b2a2d10 100644
--- a/spec/ruby/core/basicobject/singleton_method_added_spec.rb
+++ b/spec/ruby/core/basicobject/singleton_method_added_spec.rb
@@ -83,4 +83,63 @@ describe "BasicObject#singleton_method_added" do
     end
     ScratchPad.recorded.should == [:singleton_method_added, :new_method_with_define_method]
   end
+
+  describe "when singleton_method_added is undefined" do
+    it "raises NoMethodError for a metaclass" do
+      class BasicObjectSpecs::NoSingletonMethodAdded
+        class << self
+          undef_method :singleton_method_added
+        end
+
+        -> {
+          def self.foo
+          end
+        }.should raise_error(NoMethodError, /undefined method `singleton_method_added' for/)
+      end
+    end
+
+    it "raises NoMethodError for a singleton instance" do
+      object = Object.new
+      class << object
+        undef_method :singleton_method_added
+
+        -> {
+          def foo
+          end
+        }.should raise_error(NoMethodError, /undefined method `singleton_method_added' for #<Object:/)
+
+        -> {
+          define_method(:bar) {}
+        }.should raise_error(NoMethodError, /undefined method `singleton_method_added' for #<Object:/)
+      end
+
+      -> {
+        object.define_singleton_method(:baz) {}
+      }.should raise_error(NoMethodError, /undefined method `singleton_method_added' for #<Object:/)
+    end
+
+    it "calls #method_missing" do
+      ScratchPad.record []
+      object = Object.new
+      class << object
+        def method_missing(*args)
+          ScratchPad << args
+        end
+
+        undef_method :singleton_method_added
+
+        def foo
+        end
+
+        define_method(:bar) {}
+      end
+      object.define_singleton_method(:baz) {}
+
+      ScratchPad.recorded.should == [
+        [:singleton_method_added, :foo],
+        [:singleton_method_added, :bar],
+        [:singleton_method_added, :baz],
+      ]
+    end
+  end
 end
diff --git a/spec/ruby/core/dir/children_spec.rb b/spec/ruby/core/dir/children_spec.rb
index e0325a24b8..f890f54eb4 100644
--- a/spec/ruby/core/dir/children_spec.rb
+++ b/spec/ruby/core/dir/children_spec.rb
@@ -100,10 +100,18 @@ ruby_version_is "2.6" do
       a.should == %w|.dotfile.ext directory|
     end
 
-    it "accepts an options Hash" do
+    it "accepts an encoding keyword for the encoding of the entries" do
       @dir = Dir.new("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8")
-      a = @dir.children.sort
-      a.should == %w|.dotfile.ext directory|
+      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
     end
 
     it "returns children encoded with the filesystem encoding by default" do
diff --git a/spec/ruby/core/dir/each_child_spec.rb b/spec/ruby/core/dir/each_child_spec.rb
index 93b4a1aec1..684f42acc0 100644
--- a/spec/ruby/core/dir/each_child_spec.rb
+++ b/spec/ruby/core/dir/each_child_spec.rb
@@ -10,6 +10,18 @@ describe "Dir.each_child" do
     DirSpecs.delete_mock_dirs
   end
 
+  it "accepts an encoding keyword for the encoding of the entries" do
+    dirs = Dir.each_child("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8").to_a.sort
+    dirs.each {|dir| dir.encoding.should == Encoding::UTF_8}
+  end
+
+  ruby_version_is ""..."2.7" do
+    it "accepts nil options" do
+      dirs = Dir.each_child("#{DirSpecs.mock_dir}/deeply/nested", nil).to_a.sort
+      dirs.each {|dir| dir.encoding.should == Encoding.find("filesystem")}
+    end
+  end
+
   it "yields all names in an existing directory to the provided block" do
     a, b = [], []
 
diff --git a/spec/ruby/core/dir/entries_spec.rb b/spec/ruby/core/dir/entries_spec.rb
index 33568b6fc4..9aa58657db 100644
--- a/spec/ruby/core/dir/entries_spec.rb
+++ b/spec/ruby/core/dir/entries_spec.rb
@@ -35,9 +35,16 @@ describe "Dir.entries" do
     Dir.entries(p)
   end
 
-  it "accepts an options Hash" do
-    a = Dir.entries("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8").sort
-    a.should == %w|. .. .dotfile.ext directory|
+  it "accepts an encoding keyword for the encoding of the entries" do
+    dirs = Dir.entries("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8").to_a.sort
+    dirs.each {|dir| dir.encoding.should == Encoding::UTF_8}
+  end
+
+  ruby_version_is ""..."2.7" do
+    it "accepts nil options" do
+      dirs = Dir.entries("#{DirSpecs.mock_dir}/deeply/nested", nil).to_a.sort
+      dirs.each {|dir| dir.encoding.should == Encoding.find("filesystem")}
+    end
   end
 
   it "returns entries encoded with the filesystem encoding by default" do
diff --git a/spec/ruby/core/dir/foreach_spec.rb b/spec/ruby/core/dir/foreach_spec.rb
index 1560b85f8a..c3ddb27a84 100644
--- a/spec/ruby/core/dir/foreach_spec.rb
+++ b/spec/ruby/core/dir/foreach_spec.rb
@@ -39,6 +39,18 @@ describe "Dir.foreach" do
     Dir.foreach(DirSpecs.mock_dir).to_a.sort.should == DirSpecs.expected_paths
   end
 
+  it "accepts an encoding keyword for the encoding of the entries" do
+    dirs = Dir.foreach("#{DirSpecs.mock_dir}/deeply/nested", encoding: "utf-8").to_a.sort
+    dirs.each {|dir| dir.encoding.should == Encoding::UTF_8}
+  end
+
+  ruby_version_is ""..."2.7" do
+    it "accepts nil options" do
+      dirs = Dir.foreach("#{DirSpecs.mock_dir}/deeply/nested", nil).to_a.sort
+      dirs.each {|dir| dir.encoding.should == Encoding.find("filesystem")}
+    end
+  end
+
   describe "when no block is given" do
     it "returns an Enumerator" do
       Dir.foreach(DirSpecs.mock_dir).should be_an_instance_of(Enumerator)
diff --git a/spec/ruby/core/enumerator/lazy/chunk_while_spec.rb b/spec/ruby/core/enumerator/lazy/chunk_while_spec.rb
index d555089872..772bd42de9 100644
--- a/spec/ruby/core/enumerator/lazy/chunk_while_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/chunk_while_spec.rb
@@ -6,4 +6,9 @@ describe "Enumerator::Lazy#chunk_while" do
     s.lazy.chunk_while { |a, b| false }.first(100).should ==
       s.first(100).chunk_while { |a, b| false }.to_a
   end
+
+  it "should return a lazy enumerator" do
+    s = 0..Float::INFINITY
+    s.lazy.chunk_while { |a, b| false }.should be_kind_of(Enumerator::Lazy)
+  end
 end
diff --git a/spec/ruby/core/enumerator/lazy/slice_after_spec.rb b/spec/ruby/core/enumerator/lazy/slice_after_spec.rb
index 438df8d550..8b08a1ecfd 100644
--- a/spec/ruby/core/enumerator/lazy/slice_after_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/slice_after_spec.rb
@@ -6,4 +6,9 @@ describe "Enumerator::Lazy#slice_after" do
     s.lazy.slice_after { |n| true }.first(100).should ==
       s.first(100).slice_after { |n| true }.to_a
   end
+
+  it "should return a lazy enumerator" do
+    s = 0..Float::INFINITY
+    s.lazy.slice_after { |n| true }.should be_kind_of(Enumerator::Lazy)
+  end
 end
diff --git a/spec/ruby/core/enumerator/lazy/slice_before_spec.rb b/spec/ruby/core/enumerator/lazy/slice_before_spec.rb
index 6c8660c1a1..9c1ec9ba4a 100644
--- a/spec/ruby/core/enumerator/lazy/slice_before_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/slice_before_spec.rb
@@ -6,4 +6,9 @@ describe "Enumerator::Lazy#slice_before" do
     s.lazy.slice_before { |n| true }.first(100).should ==
       s.first(100).slice_before { |n| true }.to_a
   end
+
+  it "should return a lazy enumerator" do
+    s = 0..Float::INFINITY
+    s.lazy.slice_before { |n| true }.should be_kind_of(Enumerator::Lazy)
+  end
 end
diff --git a/spec/ruby/core/enumerator/lazy/slice_when_spec.rb b/spec/ruby/core/enumerator/lazy/slice_when_spec.rb
index e7673def47..f83403425d 100644
--- a/spec/ruby/core/enumerator/lazy/slice_when_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/slice_when_spec.rb
@@ -6,4 +6,9 @@ describe "Enumerator::Lazy#slice_when" do
     s.lazy.slice_when { |a, b| true }.first(100).should ==
       s.first(100).slice_when { |a, b| true }.to_a
   end
+
+  it "should return a lazy enumerator" do
+    s = 0..Float::INFINITY
+    s.lazy.slice_when { |a, b| true }.should be_kind_of(Enumerator::Lazy)
+  end
 end
diff --git a/spec/ruby/core/env/except_spec.rb b/spec/ruby/core/env/except_spec.rb
new file mode 100644
index 0000000000..cfe5865abe
--- /dev/null
+++ b/spec/ruby/core/env/except_spec.rb
@@ -0,0 +1,36 @@
+require_relative 'spec_helper'
+require_relative 'shared/to_hash'
+
+ruby_version_is "3.0" do
+  describe "ENV.except" do
+    before do
+      @orig_hash = ENV.to_hash
+    end
+
+    after do
+      ENV.replace @orig_hash
+    end
+
+    # Testing the method without arguments is covered via
+    it_behaves_like :env_to_hash, :except
+
+    it "returns a hash without the requested subset" do
+      ENV.clear
+
+      ENV['one'] = '1'
+      ENV['two'] = '2'
+      ENV['three'] = '3'
+
+      ENV.except('one', 'three').should == { 'two' => '2' }
+    end
+
+    it "ignores keys not present in the original hash" do
+      ENV.clear
+
+      ENV['one'] = '1'
+      ENV['two'] = '2'
+
+      ENV.except('one', 'three').should == { 'two' => '2' }
+    end
+  end
+end
diff --git a/spec/ruby/core/io/close_spec.rb b/spec/ruby/core/io/close_spec.rb
index dda82b34de..eb560eaf67 100644
--- a/spec/ruby/core/io/close_spec.rb
+++ b/spec/ruby/core/io/close_spec.rb
@@ -45,19 +45,36 @@ describe "IO#close" do
   end
 
   it 'raises an IOError with a clear message' do
-    read_io, write_io = IO.pipe
-    going_to_read = false
-    thread = Thread.new do
-      -> do
-        going_to_read = true
-        read_io.read
-      end.should raise_error(IOError, 'stream closed in another thread')
-    end
-
-    Thread.pass until going_to_read && thread.stop?
-    read_io.close
-    thread.join
-    write_io.close
+    matching_exception = nil
+
+    -> do
+      IOSpecs::THREAD_CLOSE_RETRIES.times do
+        read_io, write_io = IO.pipe
+        going_to_read = false
+
+        thread = Thread.new do
+          begin
+            going_to_read = true
+            read_io.read
+          rescue IOError => ioe
+            if ioe.message == IOSpecs::THREAD_CLOSE_ERROR_MESSAGE
+              matching_exception = ioe
+            end
+            # try again
+          end
+        end
+
+        # best attempt to ensure the thread is actually blocked on read
+        Thread.pass until going_to_read && thread.stop?
+        sleep(0.001)
+
+        read_io.close
+        thread.join
+        write_io.close
+
+        matching_exception&.tap {|ex| raise ex}
+      end
+    end.should raise_error(IOError, IOSpecs::THREAD_CLOSE_ERROR_MESSAGE)
   end
 end
 
diff --git a/spec/ruby/core/io/fixtures/classes.rb b/spec/ruby/core/io/fixtures/classes.rb
index 5cc42c9b44..5d81d5fcd9 100644
--- a/spec/ruby/core/io/fixtures/classes.rb
+++ b/spec/ruby/core/io/fixtures/classes.rb
@@ -1,6 +1,9 @@
 # -*- encoding: utf-8 -*-
 
 module IOSpecs
+  THREAD_CLOSE_RETRIES = 10
+  THREAD_CLOSE_ERROR_MESSAGE = 'stream closed in another thread'
+
   class SubIO < IO
   end
 
diff --git a/spec/ruby/core/kernel/fixtures/classes.rb b/spec/ruby/core/kernel/fixtures/classes.rb
index 8702c925c8..1bf5715c50 100644
--- a/spec/ruby/core/kernel/fixtures/classes.rb
+++ b/spec/ruby/core/kernel/fixtures/classes.rb
@@ -362,18 +362,19 @@ module KernelSpecs
   class RespondViaMissing
     def respond_to_missing?(method, priv=false)
       case method
-        when :handled_publicly
-          true
-        when :handled_privately
-          priv
-        when :not_handled
-          false
-        else
-          raise "Typo in method name"
+      when :handled_publicly
+        true
+      when :handled_privately
+        priv
+      when :not_handled
+        false
+      else
+        raise "Typo in method name: #{method.inspect}"
       end
     end
 
     def method_missing(method, *args)
+      raise "the method name should be a Symbol" unless Symbol === method
       "Done #{method}(#{args})"
     end
   end
diff --git a/spec/ruby/core/kernel/public_send_spec.rb b/spec/ruby/core/kernel/public_send_spec.rb
index 6b942a2e4b..4dae419ff9 100644
--- a/spec/ruby/core/kernel/public_send_spec.rb
+++ b/spec/ruby/core/kernel/public_send_spec.rb
@@ -104,5 +104,13 @@ describe "Kernel#public_send" do
     }.should raise_error(NoMethodError)
   end
 
+  it "includes `public_send` in the backtrace when passed not enough arguments" do
+    -> { public_send() }.should raise_error(ArgumentError) { |e| e.backtrace[0].should.include?("`public_send'") }
+  end
+
+  it "includes `public_send` in the backtrace when passed a single incorrect argument" do
+    -> { public_send(Object.new) }.should raise_error(TypeError) { |e| e.backtrace[0].should.include?("`public_send'") }
+  end
+
   it_behaves_like :basicobject_send, :public_send
 end
diff --git a/spec/ruby/core/kernel/shared/method.rb b/spec/ruby/core/kernel/shared/method.rb
index 3418966b1b..8b6ab23fd3 100644
--- a/spec/ruby/core/kernel/shared/method.rb
+++ b/spec/ruby/core/kernel/shared/method.rb
@@ -15,12 +15,18 @@ describe :kernel_method, shared: true do
     m.call.should == 'class done'
   end
 
-  it "returns a method object if we repond_to_missing? method" do
+  it "returns a method object if respond_to_missing?(method) is true" do
     m = KernelSpecs::RespondViaMissing.new.send(@method, :handled_publicly)
     m.should be_an_instance_of Method
     m.call(42).should == "Done handled_publicly([42])"
   end
 
+  it "the returned method object if respond_to_missing?(method) calls #method_missing with a Symbol name" do
+    m = KernelSpecs::RespondViaMissing.new.send(@method, "handled_publicly")
+    m.should be_an_instance_of Method
+    m.call(42).should == "Done handled_publicly([42])"
+  end
+
   it "raises a NameError for an invalid method name" do
     class KernelSpecs::Foo; def bar; 'done'; end; end
     -> {
diff --git a/spec/ruby/core/kernel/shared/require.rb b/spec/ruby/core/kernel/shared/require.rb
index d656b3b2f2..9a2c38be1a 100644
--- a/spec/ruby/core/kernel/shared/require.rb
+++ b/spec/ruby/core/kernel/shared/require.rb
@@ -546,8 +546,12 @@ describe :kernel_require, shared: true do
       ScratchPad.recorded.should == []
     end
 
-    it "complex, enumerator, rational and thread are already required" do
-      provided = %w[complex enumerator rational thread]
+    provided = %w[complex enumerator rational thread]
+    ruby_version_is "2.7" do
+      provided << 'ruby2_keywords'
+    end
+
+    it "#{provided.join(', ')} are already required" do
       features = ruby_exe("puts $LOADED_FEATURES", options: '--disable-gems')
       provided.each { |feature|
         features.should =~ /\b#{feature}\.(rb|so|jar)$/
diff --git a/spec/ruby/core/main/ruby2_keywords_spec.rb b/spec/ruby/core/main/ruby2_keywords_spec.rb
new file mode 100644
index 0000000000..0999cddeed
--- /dev/null
+++ b/spec/ruby/core/main/ruby2_keywords_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+ruby_version_is "2.7" do
+  describe "main.ruby2_keywords" do
+    it "is the same as Object.ruby2_keywords" do
+      main = TOPLEVEL_BINDING.receiver
+      main.should have_private_method(:ruby2_keywords)
+    end
+  end
+end
diff --git a/spec/ruby/core/module/attr_accessor_spec.rb b/spec/ruby/core/module/attr_accessor_spec.rb
index e6a6ac7b66..ba5289cbea 100644
--- a/spec/ruby/core/module/attr_accessor_spec.rb
+++ b/spec/ruby/core/module/attr_accessor_spec.rb
@@ -33,7 +33,20 @@ describe "Module#attr_accessor" do
       attr_accessor :spec_attr_accessor
     end
 
-    -> { true.spec_attr_accessor = "a" }.should raise_error(RuntimeError)
+    -> { true.spec_attr_accessor = "a" }.should raise_error(FrozenError)
+  end
+
+  it "raises FrozenError if the receiver if frozen" do
+    c = Class.new do
+      attr_accessor :foo
+    end
+    obj = c.new
+    obj.foo = 1
+    obj.foo.should == 1
+
+    obj.freeze
+    -> { obj.foo = 42 }.should raise_error(FrozenError)
+    obj.foo.should == 1
   end
 
   it "converts non string/symbol names to strings using to_str" do
diff --git a/spec/ruby/core/module/attr_writer_spec.rb b/spec/ruby/core/module/attr_writer_spec.rb
index dbf30c8144..0e9d201317 100644
--- a/spec/ruby/core/module/attr_writer_spec.rb
+++ b/spec/ruby/core/module/attr_writer_spec.rb
@@ -29,7 +29,17 @@ describe "Module#attr_writer" do
       attr_writer :spec_attr_writer
     end
 
-    -> { true.spec_attr_writer = "a" }.should raise_error(RuntimeError)
+    -> { true.spec_attr_writer = "a" }.should raise_error(FrozenError)
+  end
+
+  it "raises FrozenError if the receiver if frozen" do
+    c = Class.new do
+      attr_writer :foo
+    end
+    obj = c.new
+    obj.freeze
+
+    -> { obj.foo = 42 }.should raise_error(FrozenError)
   end
 
   it "converts non string/symbol names to strings using to_str" do
diff --git a/spec/ruby/core/module/const_defined_spec.rb b/spec/ruby/core/module/const_defined_spec.rb
index 0673adca3d..75730395e8 100644
--- a/spec/ruby/core/module/const_defined_spec.rb
+++ b/spec/ruby/core/module/const_defined_spec.rb
@@ -40,6 +40,11 @@ describe "Module#const_defined?" do
     ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4, true).should be_true
   end
 
+  it "coerces the inherit flag to a boolean" do
+    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4, nil).should be_false
+    ConstantSpecs::ContainerA::ChildA.const_defined?(:CS_CONST4, :true).should be_true
+  end
+
   it "returns true if the given String names a constant defined in the receiver" do
     ConstantSpecs.const_defined?("CS_CONST2").should == true
     ConstantSpecs.const_defined?("ModuleA").should == true
diff --git a/spec/ruby/core/module/const_get_spec.rb b/spec/ruby/core/module/const_get_spec.rb
index 0a6702903f..9f9fafe5bb 100644
--- a/spec/ruby/core/module/const_get_spec.rb
+++ b/spec/ruby/core/module/const_get_spec.rb
@@ -88,6 +88,14 @@ describe "Module#const_get" do
     end.should raise_error(NameError)
   end
 
+  it "coerces the inherit flag to a boolean" do
+    ConstantSpecs::ContainerA::ChildA.const_get(:CS_CONST4, :true).should == :const4
+
+    -> do
+      ConstantSpecs::ContainerA::ChildA.const_get(:CS_CONST1, nil)
+    end.should raise_error(NameError)
+  end
+
   it "accepts a toplevel scope qualifier" do
     ConstantSpecs.const_get("::CS_CONST1").should == :const1
   end
diff --git a/spec/ruby/core/module/refine_spec.rb b/spec/ruby/core/module/refine_spec.rb
index 54217a9326..e5f65f5f96 100644
--- a/spec/ruby/core/module/refine_spec.rb
+++ b/spec/ruby/core/module/refine_spec.rb
@@ -574,6 +574,43 @@ describe "Module#refine" do
     end
 
     ruby_version_is "" ... "2.7" do
+      it "is not honored by Kernel#public_method" do
+        klass = Class.new
+        refinement = Module.new do
+          refine klass do
+            def foo; end
+          end
+        end
+
+        -> {
+          Module.new do
+            using refinement
+            klass.new.public_method(:foo)
+          end
+        }.should raise_error(NameError, /undefined method `foo'/)
+      end
+    end
+
+    ruby_version_is "2.7" do
+      it "is honored by Kernel#public_method" 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.public_method(:foo).class
+        end
+
+        result.should == Method
+      end
+    end
+
+    ruby_version_is "" ... "2.7" do
       it "is not honored by Kernel#instance_method" do
         klass = Class.new
         refinement = Module.new do
@@ -592,7 +629,7 @@ describe "Module#refine" do
     end
 
     ruby_version_is "2.7" do
-      it "is honored by Kernel#method" do
+      it "is honored by Kernel#instance_method" do
         klass = Class.new
         refinement = Module.new do
           refine klass do
diff --git a/spec/ruby/core/proc/shared/call.rb b/spec/ruby/core/proc/shared/call.rb
index c30ea84b23..dbec34df4b 100644
--- a/spec/ruby/core/proc/shared/call.rb
+++ b/spec/ruby/core/proc/shared/call.rb
@@ -49,6 +49,9 @@ describe :proc_call_on_proc_or_lambda, shared: true do
 
     a = proc {|x| x}.send(@method, 1, 2, 3)
     a.should == 1
+
+    a = proc {|x:| x}.send(@method, 2, x: 1)
+    a.should == 1
   end
 
   it "will call #to_ary on argument and return self if return is nil" do
diff --git a/spec/ruby/core/regexp/case_compare_spec.rb b/spec/ruby/core/regexp/case_compare_spec.rb
index a621713f6f..5ae8b56c6a 100644
--- a/spec/ruby/core/regexp/case_compare_spec.rb
+++ b/spec/ruby/core/regexp/case_compare_spec.rb
@@ -22,4 +22,14 @@ describe "Regexp#===" do
     (/abc/ === nil).should be_false
     (/abc/ === /abc/).should be_false
   end
+
+  it "uses #to_str on string-like objects" do
+    stringlike = Class.new do
+      def to_str
+        "abc"
+      end
+    end.new
+
+    (/abc/ === stringlike).should be_true
+  end
 end
diff --git a/spec/ruby/core/signal/trap_spec.rb b/spec/ruby/core/signal/trap_spec.rb
index 831a5ee23e..45879b7147 100644
--- a/spec/ruby/core/signal/trap_spec.rb
+++ b/spec/ruby/core/signal/trap_spec.rb
@@ -49,7 +49,21 @@ platform_is_not :windows do
 
     it "registers an handler doing nothing with :IGNORE" do
       Signal.trap :HUP, :IGNORE
+      Signal.trap(:HUP, @saved_trap).should == "IGNORE"
+    end
+
+    it "can register a new handler after :IGNORE" do
+      Signal.trap :HUP, :IGNORE
+
+      done = false
+      Signal.trap(:HUP) do
+        ScratchPad.record :block_trap
+        done = true
+      end
+
       Process.kill(:HUP, Process.pid).should == 1
+      Thread.pass until done
+      ScratchPad.recorded.should == :block_trap
     end
 
     it "ignores the signal when passed nil" do
diff --git a/spec/ruby/core/string/scrub_spec.rb b/spec/ruby/core/string/scrub_spec.rb
index 86fd4e85ba..b513acfb70 100644
--- a/spec/ruby/core/string/scrub_spec.rb
+++ b/spec/ruby/core/string/scrub_spec.rb
@@ -105,4 +105,18 @@ describe "String#scrub!" do
     input.scrub! { |b| "<?>" }
     input.should == "a<?>"
   end
+
+  it "maintains the state of frozen strings that are already valid" do
+    input = "a"
+    input.freeze
+    input.scrub!
+    input.frozen?.should be_true
+  end
+
+  it "preserves the instance variables of already valid strings" do
+    input = "a"
+    input.instance_variable_set(:@a, 'b')
+    input.scrub!
+    input.instance_variable_get(:@a).should == 'b'
+  end
 end
diff --git a/spec/ruby/core/time/shared/now.rb b/spec/ruby/core/time/shared/now.rb
index 80f66a1134..f4018d72f4 100644
--- a/spec/ruby/core/time/shared/now.rb
+++ b/spec/ruby/core/time/shared/now.rb
@@ -19,15 +19,15 @@ describe :time_now, shared: true do
   end
 
   it "has at least microsecond precision" do
-    times = []
-    10_000.times do
-      times << Time.now.nsec
-    end
-
     # The clock should not be less accurate than expected (times should
     # not all be a multiple of the next precision up, assuming precisions
     # are multiples of ten.)
     expected = 1_000
-    times.select { |t| t % (expected * 10) == 0  }.size.should_not == times.size
+    t = 0
+    10_000.times.find do
+      t = Time.now.nsec
+      t % (expected * 10) != 0
+    end
+    (t % (expected * 10)).should != 0
   end
 end
diff --git a/spec/ruby/fixtures/code/concurrent.rb b/spec/ruby/fixtures/code/concurrent.rb
index 054b8fc055..b3602a3db4 100644
--- a/spec/ruby/fixtures/code/concurrent.rb
+++ b/spec/ruby/fixtures/code/concurrent.rb
@@ -2,7 +2,7 @@ ScratchPad.recorded << :con_pre
 Thread.current[:in_concurrent_rb] = true
 
 if t = Thread.current[:wait_for]
-  Thread.pass until t.backtrace && t.backtrace.any? { |call| call.include? 'require' }
+  Thread.pass until t.backtrace && t.backtrace.any? { |call| call.include? 'require' } && t.stop?
 end
 
 if Thread.current[:con_raise]
diff --git a/spec/ruby/language/regexp/back-references_spec.rb b/spec/ruby/language/regexp/back-references_spec.rb
index e8df8725c5..26750c20c5 100644
--- a/spec/ruby/language/regexp/back-references_spec.rb
+++ b/spec/ruby/language/regexp/back-references_spec.rb
@@ -63,6 +63,11 @@ describe "Regexps with back-references" do
     (/\10()()()()()()()()()()/ =~ "\x08").should == 0
   end
 
+  it "fails when trying to match a backreference to an unmatched capture group" do
+    /\1()/.match("").should == nil
+    /(?:(a)|b)\1/.match("b").should == nil
+  end
+
   it "ignores backreferences > 1000" do
     /\99999/.match("99999")[0].should == "99999"
   end
diff --git a/spec/ruby/language/regexp/empty_checks_spec.rb b/spec/ruby/language/regexp/empty_checks_spec.rb
new file mode 100644
index 0000000000..391e65b003
--- /dev/null
+++ b/spec/ruby/language/regexp/empty_checks_spec.rb
@@ -0,0 +1,135 @@
+require_relative '../../spec_helper'
+require_relative '../fixtures/classes'
+
+describe "empty checks in Regexps" do
+
+  it "allow extra empty iterations" do
+    /()?/.match("").to_a.should == ["", ""]
+    /(a*)?/.match("").to_a.should == ["", ""]
+    /(a*)*/.match("").to_a.should == ["", ""]
+    # The bounds are high to avoid DFA-based matchers in implementations
+    # and to check backtracking behavior.
+    /(?:a|()){500,1000}/.match("a" * 500).to_a.should == ["a" * 500, ""]
+
+    # Variations with non-greedy loops.
+    /()??/.match("").to_a.should == ["", nil]
+    /(a*?)?/.match("").to_a.should == ["", ""]
+    /(a*)??/.match("").to_a.should == ["", nil]
+    /(a*?)??/.match("").to_a.should == ["", nil]
+    /(a*?)*/.match("").to_a.should == ["", ""]
+    /(a*)*?/.match("").to_a.should == ["", nil]
+    /(a*?)*?/.match("").to_a.should == ["", nil]
+  end
+
+  it "allow empty iterations in the middle of a loop" do
+    # One empty iteration between a's and b's.
+    /(a|\2b|())*/.match("aaabbb").to_a.should == ["aaabbb", "", ""]
+    /(a|\2b|()){2,4}/.match("aaabbb").to_a.should == ["aaa", "", ""]
+
+    # Two empty iterations between a's and b's.
+    /(a|\2b|\3()|())*/.match("aaabbb").to_a.should == ["aaabbb", "", "", ""]
+    /(a|\2b|\3()|()){2,4}/.match("aaabbb").to_a.should == ["aaa", "", nil, ""]
+
+    # Check that the empty iteration correctly updates the loop counter.
+    /(a|\2b|()){20,24}/.match("a" * 20 + "b" * 5).to_a.should == ["a" * 20 + "b" * 3, "b", ""]
+
+    # Variations with non-greedy loops.
+    /(a|\2b|())*?/.match("aaabbb").to_a.should == ["", nil, nil]
+    /(a|\2b|()){2,4}/.match("aaabbb").to_a.should == ["aaa", "", ""]
+    /(a|\2b|\3()|())*?/.match("aaabbb").to_a.should == ["", nil, nil, nil]
+    /(a|\2b|\3()|()){2,4}/.match("aaabbb").to_a.should == ["aaa", "", nil, ""]
+    /(a|\2b|()){20,24}/.match("a" * 20 + "b" * 5).to_a.should == ["a" * 20 + "b" * 3, "b", ""]
+  end
+
+  it "make the Regexp proceed past the quantified expression on failure" do
+    # If the contents of the ()* quantified group are empty (i.e., they fail
+    # the empty check), the loop will abort. It will not try to backtrack
+    # and try other alternatives (e.g. matching the "a") like in other Regexp
+    # dialects such as ECMAScript.
+    /(?:|a)*/.match("aaa").to_a.should == [""]
+    /(?:()|a)*/.match("aaa").to_a.should == ["", ""]
+    /(|a)*/.match("aaa").to_a.should == ["", ""]
+    /(()|a)*/.match("aaa").to_a.should == ["", "", ""]
+
+    # Same expressions, but with backreferences, to force the use of non-DFA-based
+    # engines.
+    /()\1(?:|a)*/.match("aaa").to_a.should == ["", ""]
+    /()\1(?:()|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()\1(|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()\1(()|a)*/.match("aaa").to_a.should == ["", "", "", ""]
+
+    # Variations with other zero-width contents of the quantified
+    # group: backreferences, capture groups, lookarounds
+    /()(?:\1|a)*/.match("aaa").to_a.should == ["", ""]
+    /()(?:()\1|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()(?:(\1)|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()(?:\1()|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()(\1|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()(()\1|a)*/.match("aaa").to_a.should == ["", "", "", ""]
+    /()((\1)|a)*/.match("aaa").to_a.should == ["", "", "", ""]
+    /()(\1()|a)*/.match("aaa").to_a.should == ["", "", "", ""]
+
+    /(?:(?=a)|a)*/.match("aaa").to_a.should == [""]
+    /(?:(?=a)()|a)*/.match("aaa").to_a.should == ["", ""]
+    /(?:()(?=a)|a)*/.match("aaa").to_a.should == ["", ""]
+    /(?:((?=a))|a)*/.match("aaa").to_a.should == ["", ""]
+    /()\1(?:(?=a)|a)*/.match("aaa").to_a.should == ["", ""]
+    /()\1(?:(?=a)()|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()\1(?:()(?=a)|a)*/.match("aaa").to_a.should == ["", "", ""]
+    /()\1(?:((?=a))|a)*/.match("aaa").to_a.should == ["", "", ""]
+
+    # Variations with non-greedy loops.
+    /(?:|a)*?/.match("aaa").to_a.should == [""]
+    /(?:()|a)*?/.match("aaa").to_a.should == ["", nil]
+    /(|a)*?/.match("aaa").to_a.should == ["", nil]
+    /(()|a)*?/.match("aaa").to_a.should == ["", nil, nil]
+
+    /()\1(?:|a)*?/.match("aaa").to_a.should == ["", ""]
+    /()\1(?:()|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()\1(|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()\1(()|a)*?/.match("aaa").to_a.should == ["", "", nil, nil]
+
+    /()(?:\1|a)*?/.match("aaa").to_a.should == ["", ""]
+    /()(?:()\1|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()(?:(\1)|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()(?:\1()|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()(\1|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()(()\1|a)*?/.match("aaa").to_a.should == ["", "", nil, nil]
+    /()((\1)|a)*?/.match("aaa").to_a.should == ["", "", nil, nil]
+    /()(\1()|a)*?/.match("aaa").to_a.should == ["", "", nil, nil]
+
+    /(?:(?=a)|a)*?/.match("aaa").to_a.should == [""]
+    /(?:(?=a)()|a)*?/.match("aaa").to_a.should == ["", nil]
+    /(?:()(?=a)|a)*?/.match("aaa").to_a.should == ["", nil]
+    /(?:((?=a))|a)*?/.match("aaa").to_a.should == ["", nil]
+    /()\1(?:(?=a)|a)*?/.match("aaa").to_a.should == ["", ""]
+    /()\1(?:(?=a)()|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()\1(?:()(?=a)|a)*?/.match("aaa").to_a.should == ["", "", nil]
+    /()\1(?:((?=a))|a)*?/.match("aaa").to_a.should == ["", "", nil]
+  end
+
+  it "shouldn't cause the Regexp parser to get stuck in a loop" do
+    /(|a|\2b|())*/.match("aaabbb").to_a.should == ["", "", nil]
+    /(a||\2b|())*/.match("aaabbb").to_a.should == ["aaa", "", nil]
+    /(a|\2b||())*/.match("aaabbb").to_a.should == ["aaa", "", nil]
+    /(a|\2b|()|)*/.match("aaabbb").to_a.should == ["aaabbb", "", ""]
+    /(()|a|\3b|())*/.match("aaabbb").to_a.should == ["", "", "", nil]
+    /(a|()|\3b|())*/.match("aaabbb").to_a.should == ["aaa", "", "", nil]
+    /(a|\2b|()|())*/.match("aaabbb").to_a.should == ["aaabbb", "", "", nil]
+    /(a|\3b|()|())*/.match("aaabbb").to_a.should == ["aaa", "", "", nil]
+    /(a|()|())*/.match("aaa").to_a.should == ["aaa", "", "", nil]
+    /^(()|a|())*$/.match("aaa").to_a.should == ["aaa", "", "", nil]
+
+    # Variations with non-greedy loops.
+    /(|a|\2b|())*?/.match("aaabbb").to_a.should == ["", nil, nil]
+    /(a||\2b|())*?/.match("aaabbb").to_a.should == ["", nil, nil]
+    /(a|\2b||())*?/.match("aaabbb").to_a.should == ["", nil, nil]
+    /(a|\2b|()|)*?/.match("aaabbb").to_a.should == ["", nil, nil]
+    /(()|a|\3b|())*?/.match("aaabbb").to_a.should == ["", nil, nil, nil]
+    /(a|()|\3b|())*?/.match("aaabbb").to_a.should == ["", nil, nil, nil]
+    /(a|\2b|()|())*?/.match("aaabbb").to_a.should == ["", nil, nil, nil]
+    /(a|\3b|()|())*?/.match("aaabbb").to_a.should == ["", nil, nil, nil]
+    /(a|()|())*?/.match("aaa").to_a.should == ["", nil, nil, nil]
+    /^(()|a|())*?$/.match("aaa").to_a.should == ["aaa", "a", "", nil]
+  end
+end
diff --git a/spec/ruby/language/regexp/repetition_spec.rb b/spec/ruby/language/regexp/repetition_spec.rb
index 295b3bf553..9a191d74e2 100644
--- a/spec/ruby/language/regexp/repetition_spec.rb
+++ b/spec/ruby/language/regexp/repetition_spec.rb
@@ -128,4 +128,15 @@ describe "Regexps with repetition" do
       RUBY
     end
   end
+
+  it "treats ? after {n} quantifier as another quantifier, not as non-greedy marker" do
+    /a{2}?/.match("").to_a.should == [""]
+  end
+
+  it "matches zero-width capture groups in optional iterations of loops" do
+    /()?/.match("").to_a.should == ["", ""]
+    /(a*)?/.match("").to_a.should == ["", ""]
+    /(a*)*/.match("").to_a.should == ["", ""]
+    /(?:a|()){500,1000}/.match("a" * 500).to_a.should == ["a" * 500, ""]
+  end
 end
diff --git a/spec/ruby/library/matrix/exponent_spec.rb b/spec/ruby/library/matrix/exponent_spec.rb
index 71c5f97769..a310cc2c70 100644
--- a/spec/ruby/library/matrix/exponent_spec.rb
+++ b/spec/ruby/library/matrix/exponent_spec.rb
@@ -34,7 +34,7 @@ describe "Matrix#**" do
       end
     end
 
-    ruby_bug '#17521', ''...'3.0.1' do
+    ruby_version_is '3.0.1' do # https://bugs.ruby-lang.org/issues/17521
       describe "that is 0" do
         it "returns the identity for square matrices" do
           m = Matrix[ [1, 1], [1, 1] ]
diff --git a/spec/ruby/library/set/initialize_spec.rb b/spec/ruby/library/set/initialize_spec.rb
index 887cae45fc..76ebc0a20a 100644
--- a/spec/ruby/library/set/initialize_spec.rb
+++ b/spec/ruby/library/set/initialize_spec.rb
@@ -14,6 +14,31 @@ describe "Set#initialize" do
     s.should include(3)
   end
 
+  it "uses #each_entry on the provided Enumerable" do
+    enumerable = MockObject.new('mock-enumerable')
+    enumerable.should_receive(:each_entry).and_yield(1).and_yield(2).and_yield(3)
+    s = Set.new(enumerable)
+    s.size.should eql(3)
+    s.should include(1)
+    s.should include(2)
+    s.should include(3)
+  end
+
+  it "uses #each on the provided Enumerable if it does not respond to #each_entry" do
+    enumerable = MockObject.new('mock-enumerable')
+    enumerable.should_receive(:each).and_yield(1).and_yield(2).and_yield(3)
+    s = Set.new(enumerable)
+    s.size.should eql(3)
+    s.should include(1)
+    s.should include(2)
+    s.should include(3)
+  end
+
+  it "raises if the provided Enumerable does not respond to #each_entry or #each" do
+    enumerable = MockObject.new('mock-enumerable')
+    -> { Set.new(enumerable) }.should raise_error(ArgumentError, "value must be enumerable")
+  end
+
   it "should initialize with empty array and set" do
     s = Set.new([])
     s.size.should eql(0)
diff --git a/spec/ruby/optional/capi/exception_spec.rb b/spec/ruby/optional/capi/exception_spec.rb
index 9e82e5c7dd..b0a8a2860e 100644
--- a/spec/ruby/optional/capi/exception_spec.rb
+++ b/spec/ruby/optional/capi/exception_spec.rb
@@ -36,6 +36,50 @@ describe "C-API Exception function" do
       runtime_error.set_backtrace []
       -> { @s.rb_exc_raise(runtime_error) }.should raise_error(RuntimeError, '42')
     end
+
+    it "sets $! to the raised exception when not rescuing from an another exception" do
+      runtime_error = RuntimeError.new '42'
+      runtime_error.set_backtrace []
+      begin
+        @s.rb_exc_raise(runtime_error)
+      rescue
+        $!.should == runtime_error
+      end
+    end
+
+    it "sets $! to the raised exception when $! when rescuing from an another exception" do
+      runtime_error = RuntimeError.new '42'
+      runtime_error.set_backtrace []
+      begin
+        begin
+          raise StandardError
+        rescue
+          @s.rb_exc_raise(runtime_error)
+        end
+      rescue
+        $!.should == runtime_error
+      end
+    end
+  end
+
+  describe "rb_errinfo" do
+    it "is cleared when entering a C method" do
+      begin
+        raise StandardError
+      rescue
+        $!.class.should == StandardError
+        @s.rb_errinfo().should == nil
+      end
+    end
+
+    it "does not clear $! in the calling method" do
+      begin
+        raise StandardError
+      rescue
+        @s.rb_errinfo()
+        $!.class.should == StandardError
+      end
+    end
   end
 
   describe "rb_set_errinfo" do
diff --git a/spec/ruby/optional/capi/ext/exception_spec.c b/spec/ruby/optional/capi/ext/exception_spec.c
index 7250792b70..e1114aabb8 100644
--- a/spec/ruby/optional/capi/ext/exception_spec.c
+++ b/spec/ruby/optional/capi/ext/exception_spec.c
@@ -8,6 +8,10 @@
 extern "C" {
 #endif
 
+VALUE exception_spec_rb_errinfo(VALUE self) {
+  return rb_errinfo();
+}
+
 VALUE exception_spec_rb_exc_new(VALUE self, VALUE str) {
   char *cstr = StringValuePtr(str);
   return rb_exc_new(rb_eException, cstr, strlen(cstr));
@@ -41,6 +45,7 @@ VALUE exception_spec_rb_make_exception(VALUE self, VALUE ary) {
 
 void Init_exception_spec(void) {
   VALUE cls = rb_define_class("CApiExceptionSpecs", rb_cObject);
+  rb_define_method(cls, "rb_errinfo", exception_spec_rb_errinfo, 0);
   rb_define_method(cls, "rb_exc_new", exception_spec_rb_exc_new, 1);
   rb_define_method(cls, "rb_exc_new2", exception_spec_rb_exc_new2, 1);
   rb_define_method(cls, "rb_exc_new3", exception_spec_rb_exc_new3, 1);
diff --git a/spec/ruby/optional/capi/ext/io_spec.c b/spec/ruby/optional/capi/ext/io_spec.c
index 73e6804013..b4ffe9207a 100644
--- a/spec/ruby/optional/capi/ext/io_spec.c
+++ b/spec/ruby/optional/capi/ext/io_spec.c
@@ -227,6 +227,16 @@ static VALUE io_spec_errno_set(VALUE self, VALUE val) {
   return val;
 }
 
+VALUE io_spec_mode_sync_flag(VALUE self, VALUE io) {
+  rb_io_t *fp;
+  GetOpenFile(io, fp);
+  if (fp->mode & FMODE_SYNC) {
+    return Qtrue;
+  } else {
+    return Qfalse;
+  }
+}
+
 void Init_io_spec(void) {
   VALUE cls = rb_define_class("CApiIOSpecs", rb_cObject);
   rb_define_method(cls, "GetOpenFile_fd", io_spec_GetOpenFile_fd, 1);
@@ -251,6 +261,7 @@ void Init_io_spec(void) {
   rb_define_method(cls, "rb_fd_fix_cloexec", io_spec_rb_fd_fix_cloexec, 1);
   rb_define_method(cls, "rb_cloexec_open", io_spec_rb_cloexec_open, 3);
   rb_define_method(cls, "errno=", io_spec_errno_set, 1);
+  rb_define_method(cls, "rb_io_mode_sync_flag", io_spec_mode_sync_flag, 1);
 }
 
 #ifdef __cplusplus
diff --git a/spec/ruby/optional/capi/ext/kernel_spec.c b/spec/ruby/optional/capi/ext/kernel_spec.c
index 4048684b2c..a1960a2fe7 100644
--- a/spec/ruby/optional/capi/ext/kernel_spec.c
+++ b/spec/ruby/optional/capi/ext/kernel_spec.c
@@ -310,10 +310,6 @@ static VALUE kernel_spec_rb_make_backtrace(VALUE self) {
   return rb_make_backtrace();
 }
 
-static VALUE kernel_spec_rb_obj_method(VALUE self, VALUE obj, VALUE method) {
-  return rb_obj_method(obj, method);
-}
-
 static VALUE kernel_spec_rb_funcall3(VALUE self, VALUE obj, VALUE method) {
   return rb_funcall3(obj, SYM2ID(method), 0, NULL);
 }
@@ -366,7 +362,6 @@ void Init_kernel_spec(void) {
   rb_define_method(cls, "rb_set_end_proc", kernel_spec_rb_set_end_proc, 1);
   rb_define_method(cls, "rb_f_sprintf", kernel_spec_rb_f_sprintf, 1);
   rb_define_method(cls, "rb_make_backtrace", kernel_spec_rb_make_backtrace, 0);
-  rb_define_method(cls, "rb_obj_method", kernel_spec_rb_obj_method, 2);
   rb_define_method(cls, "rb_funcall3", kernel_spec_rb_funcall3, 2);
   rb_define_method(cls, "rb_funcall_many_args", kernel_spec_rb_funcall_many_args, 2);
   rb_define_method(cls, "rb_funcall_with_block", kernel_spec_rb_funcall_with_block, 3);
diff --git a/spec/ruby/optional/capi/ext/object_spec.c b/spec/ruby/optional/capi/ext/object_spec.c
index a229301f40..24f9de260e 100644
--- a/spec/ruby/optional/capi/ext/object_spec.c
+++ b/spec/ruby/optional/capi/ext/object_spec.c
@@ -147,6 +147,10 @@ static VALUE object_specs_rb_obj_method_arity(VALUE self, VALUE obj, VALUE mid)
   return INT2FIX(rb_obj_method_arity(obj, SYM2ID(mid)));
 }
 
+static VALUE object_specs_rb_obj_method(VALUE self, VALUE obj, VALUE method) {
+  return rb_obj_method(obj, method);
+}
+
 static VALUE object_spec_rb_obj_taint(VALUE self, VALUE obj) {
   return rb_obj_taint(obj);
 }
@@ -420,6 +424,7 @@ void Init_object_spec(void) {
   rb_define_method(cls, "rb_obj_is_instance_of", so_instance_of, 2);
   rb_define_method(cls, "rb_obj_is_kind_of", so_kind_of, 2);
   rb_define_method(cls, "rb_obj_method_arity", object_specs_rb_obj_method_arity, 2);
+  rb_define_method(cls, "rb_obj_method", object_specs_rb_obj_method, 2);
   rb_define_method(cls, "rb_obj_taint", object_spec_rb_obj_taint, 1);
   rb_define_method(cls, "rb_require", so_require, 0);
   rb_define_method(cls, "rb_respond_to", so_respond_to, 2);
@@ -462,7 +467,7 @@ void Init_object_spec(void) {
   rb_define_method(cls, "rb_undef_alloc_func", undef_alloc_func, 1);
   rb_define_method(cls, "speced_allocator?", speced_allocator_p, 1);
   rb_define_method(cls, "custom_alloc_func?", custom_alloc_func_p, 1);
-  rb_define_method(cls, "not_implemented_method", rb_f_notimplement, 1);
+  rb_define_method(cls, "not_implemented_method", rb_f_notimplement, -1);
 }
 
 #ifdef __cplusplus
diff --git a/spec/ruby/optional/capi/io_spec.rb b/spec/ruby/optional/capi/io_spec.rb
index c3c1189a43..489a01c515 100644
--- a/spec/ruby/optional/capi/io_spec.rb
+++ b/spec/ruby/optional/capi/io_spec.rb
@@ -375,3 +375,29 @@ describe "rb_cloexec_open" do
     @io.close_on_exec?.should be_true
   end
 end
+
+describe "rb_io_t modes flags" do
+  before :each do
+    @o = CApiIOSpecs.new
+    @name = tmp("c_api_rb_io_specs")
+    touch @name
+  end
+
+  after :each do
+    rm_r @name
+  end
+
+  it "has the sync flag set if the IO object is synced in Ruby" do
+    File.open(@name) { |io|
+      io.sync = true
+      @o.rb_io_mode_sync_flag(io).should == true
+    }
+  end
+
+  it "has the sync flag unset if the IO object is not synced in Ruby" do
+    File.open(@name) { |io|
+      io.sync = false
+      @o.rb_io_mode_sync_flag(io).should == false
+    }
+  end
+end
diff --git a/spec/ruby/optional/capi/kernel_spec.rb b/spec/ruby/optional/capi/kernel_spec.rb
index 7539e0c01c..ab66f7fa9e 100644
--- a/spec/ruby/optional/capi/kernel_spec.rb
+++ b/spec/ruby/optional/capi/kernel_spec.rb
@@ -559,20 +559,6 @@ describe "C-API Kernel function" do
     end
   end
 
-  describe "rb_obj_method" do
-    it "returns the method object for a symbol" do
-      method = @s.rb_obj_method("test", :size)
-      method.owner.should == String
-      method.name.to_sym.should == :size
-    end
-
-    it "returns the method object for a string" do
-      method = @s.rb_obj_method("test", "size")
-      method.owner.should == String
-      method.name.to_sym.should == :size
-    end
-  end
-
   describe "rb_funcall3" do
     before :each do
       @obj = Object.new
diff --git a/spec/ruby/optional/capi/module_spec.rb b/spec/ruby/optional/capi/module_spec.rb
index 9a0c707263..750d64367d 100644
--- a/spec/ruby/optional/capi/module_spec.rb
+++ b/spec/ruby/optional/capi/module_spec.rb
@@ -246,11 +246,23 @@ describe "CApiModule" do
       cls.new.test_method.should == :test_method
     end
 
+    it "returns the correct arity of the method in class" do
+      cls = Class.new
+      @m.rb_define_method(cls, "test_method")
+      cls.new.method(:test_method).arity.should == 0
+    end
+
     it "defines a method on a module" do
       mod = Module.new
       @m.rb_define_method(mod, "test_method")
       mod.should have_instance_method(:test_method)
     end
+
+    it "returns the correct arity of the method in module" do
+      mod = Module.new
+      @m.rb_define_method(mod, "test_method")
+      mod.instance_method(:test_method).arity.should == 0
+    end
   end
 
   describe "rb_define_module_function" do
@@ -263,12 +275,23 @@ describe "CApiModule" do
       @mod.test_module_function.should == :test_method
     end
 
+    it "returns the correct arity of the module function" do
+      @mod.method(:test_module_function).arity.should == 0
+    end
+
     it "defines a private instance method" do
       cls = Class.new
       cls.include(@mod)
 
       cls.should have_private_instance_method(:test_module_function)
     end
+
+    it "returns the correct arity for private instance method" do
+      cls = Class.new
+      cls.include(@mod)
+
+      @mod.instance_method(:test_module_function).arity.should == 0
+    end
   end
 
   describe "rb_define_private_method" do
diff --git a/spec/ruby/optional/capi/object_spec.rb b/spec/ruby/optional/capi/object_spec.rb
index 83d8f023b3..9b3a0593b0 100644
--- a/spec/ruby/optional/capi/object_spec.rb
+++ b/spec/ruby/optional/capi/object_spec.rb
@@ -161,6 +161,20 @@ describe "CApiObject" do
     end
   end
 
+  describe "rb_obj_method" do
+    it "returns the method object for a symbol" do
+      method = @o.rb_obj_method("test", :size)
+      method.owner.should == String
+      method.name.to_sym.should == :size
+    end
+
+    it "returns the method object for a string" do
+      method = @o.rb_obj_method("test", "size")
+      method.owner.should == String
+      method.name.to_sym.should == :size
+    end
+  end
+
   describe "rb_method_boundp" do
     it "returns true when the given method is bound" do
       @o.rb_method_boundp(Object, :class, true).should == true
diff --git a/spec/ruby/optional/capi/thread_spec.rb b/spec/ruby/optional/capi/thread_spec.rb
index df454d1ea8..3b788122ac 100644
--- a/spec/ruby/optional/capi/thread_spec.rb
+++ b/spec/ruby/optional/capi/thread_spec.rb
@@ -102,13 +102,13 @@ describe "C-API Thread function" do
   end
 
   describe "rb_thread_call_without_gvl" do
-    it "runs a C function with the global lock unlocked" do
+    it "runs a C function with the global lock unlocked and can be woken by Thread#wakeup" do
       thr = Thread.new do
         @t.rb_thread_call_without_gvl
       end
 
       # Wait until it's blocking...
-      Thread.pass while thr.status and thr.status != "sleep"
+      Thread.pass until thr.stop?
 
       # The thread status is set to sleep by rb_thread_call_without_gvl(),
       # but the thread might not be in the blocking read(2) yet, so wait a bit.
@@ -121,14 +121,48 @@ describe "C-API Thread function" do
       thr.value.should be_true
     end
 
-    guard -> { platform_is :mingw and ruby_version_is ""..."2.7" } do
+    platform_is_not :windows do
+      it "runs a C function with the global lock unlocked and can be woken by a signal" do
+        # Ruby signal handlers run on the main thread, so we need to reverse roles here and have a thread interrupt us
+        thr = Thread.current
+        thr.should == Thread.main
+
+        going_to_block = false
+        interrupter = Thread.new do
+          # Wait until it's blocking...
+          Thread.pass until going_to_block and thr.stop?
+
+          # The thread status is set to sleep by rb_thread_call_without_gvl(),
+          # but the thread might not be in the blocking read(2) yet, so wait a bit.
+          sleep 0.1
+
+          # Wake it up by sending a signal
+          done = false
+          prev_handler = Signal.trap(:HUP) { done = true }
+          begin
+            Process.kill :HUP, Process.pid
+            sleep 0.001 until done
+          ensure
+            Signal.trap(:HUP, prev_handler)
+          end
+        end
+
+        going_to_block = true
+        # Make sure it stopped and we got a proper value
+        @t.rb_thread_call_without_gvl.should be_true
+
+        interrupter.join
+      end
+    end
+
+    guard_not -> { platform_is :mingw and ruby_version_is ""..."2.7" } do
       it "runs a C function with the global lock unlocked and unlocks IO with the generic RUBY_UBF_IO" do
         thr = Thread.new do
           @t.rb_thread_call_without_gvl_with_ubf_io
         end
 
         # Wait until it's blocking...
-        Thread.pass while thr.status and thr.status != "sleep"
+        Thread.pass until thr.stop?
 
         # The thread status is set to sleep by rb_thread_call_without_gvl(),
         # but the thread might not be in the blocking read(2) yet, so wait a bit.