10 files changed, 54 insertions, 28 deletions
diff --git a/spec/ruby/core/nil/case_compare_spec.rb b/spec/ruby/core/nil/case_compare_spec.rb
new file mode 100644
index 0000000000..142560c6f5
--- /dev/null
+++ b/spec/ruby/core/nil/case_compare_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "NilClass#===" do
+  it "returns true for nil" do
+    (nil === nil).should == true
+  end
+
+  it "returns false for non-nil object" do
+    (nil === 1).should == false
+    (nil === "").should == false
+    (nil === Object).should == false
+  end
+end
diff --git a/spec/ruby/core/nil/dup_spec.rb b/spec/ruby/core/nil/dup_spec.rb
index 0324b3f1f4..e0be9540a6 100644
--- a/spec/ruby/core/nil/dup_spec.rb
+++ b/spec/ruby/core/nil/dup_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../spec_helper'
 
 describe "NilClass#dup" do
   it "returns self" do
-    nil.dup.should equal(nil)
+    nil.dup.should.equal?(nil)
   end
 end
diff --git a/spec/ruby/core/nil/match_spec.rb b/spec/ruby/core/nil/match_spec.rb
index 3f69312bfe..27ebc53c3d 100644
--- a/spec/ruby/core/nil/match_spec.rb
+++ b/spec/ruby/core/nil/match_spec.rb
@@ -1,19 +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 = nil
 
-      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 == nil
+      (o =~ 'Object').should == nil
+      (o =~ Object).should == nil
+      (o =~ Object.new).should == nil
+      (o =~ nil).should == nil
+      (o =~ false).should == nil
+      (o =~ true).should == nil
     end
   end
+
+  it "should not warn" do
+    -> { nil =~ /a/ }.should_not complain(verbose: true)
+  end
 end
diff --git a/spec/ruby/core/nil/nil_spec.rb b/spec/ruby/core/nil/nil_spec.rb
index 47db0c5cf0..2cf97621c6 100644
--- a/spec/ruby/core/nil/nil_spec.rb
+++ b/spec/ruby/core/nil/nil_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../spec_helper'
 
 describe "NilClass#nil?" do
   it "returns true" do
-    nil.nil?.should == true
+    nil.should.nil?
   end
 end
diff --git a/spec/ruby/core/nil/nilclass_spec.rb b/spec/ruby/core/nil/nilclass_spec.rb
index 7f6d8af25d..55c5d0eba7 100644
--- a/spec/ruby/core/nil/nilclass_spec.rb
+++ b/spec/ruby/core/nil/nilclass_spec.rb
@@ -4,12 +4,12 @@ describe "NilClass" do
   it ".allocate raises a TypeError" do
     -> do
       NilClass.allocate
-    end.should raise_error(TypeError)
+    end.should.raise(TypeError)
   end
 
   it ".new is undefined" do
     -> do
       NilClass.new
-    end.should raise_error(NoMethodError)
+    end.should.raise(NoMethodError)
   end
 end
diff --git a/spec/ruby/core/nil/rationalize_spec.rb b/spec/ruby/core/nil/rationalize_spec.rb
index 84d6e6f056..69fb257a7f 100644
--- a/spec/ruby/core/nil/rationalize_spec.rb
+++ b/spec/ruby/core/nil/rationalize_spec.rb
@@ -10,7 +10,7 @@ describe "NilClass#rationalize" do
   end
 
   it "raises ArgumentError when passed more than one argument" do
-    -> { nil.rationalize(0.1, 0.1) }.should raise_error(ArgumentError)
-    -> { nil.rationalize(0.1, 0.1, 2) }.should raise_error(ArgumentError)
+    -> { nil.rationalize(0.1, 0.1) }.should.raise(ArgumentError)
+    -> { nil.rationalize(0.1, 0.1, 2) }.should.raise(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/nil/singleton_method_spec.rb b/spec/ruby/core/nil/singleton_method_spec.rb
new file mode 100644
index 0000000000..f121b42f81
--- /dev/null
+++ b/spec/ruby/core/nil/singleton_method_spec.rb
@@ -0,0 +1,13 @@
+require_relative '../../spec_helper'
+
+describe "NilClass#singleton_method" do
+  it "raises regardless of whether NilClass defines the method" do
+    -> { nil.singleton_method(:foo) }.should.raise(NameError)
+    begin
+      def (nil).foo; end
+      -> { nil.singleton_method(:foo) }.should.raise(NameError)
+    ensure
+      NilClass.send(:remove_method, :foo)
+    end
+  end
+end
diff --git a/spec/ruby/core/nil/to_c_spec.rb b/spec/ruby/core/nil/to_c_spec.rb
index e0052be5bd..f449ddb6a3 100644
--- a/spec/ruby/core/nil/to_c_spec.rb
+++ b/spec/ruby/core/nil/to_c_spec.rb
@@ -2,6 +2,6 @@ require_relative '../../spec_helper'
 
 describe "NilClass#to_c" do
   it "returns Complex(0, 0)" do
-    nil.to_c.should eql(Complex(0, 0))
+    nil.to_c.should.eql?(Complex(0, 0))
   end
 end
diff --git a/spec/ruby/core/nil/to_i_spec.rb b/spec/ruby/core/nil/to_i_spec.rb
index 099792ef68..d3d088e999 100644
--- a/spec/ruby/core/nil/to_i_spec.rb
+++ b/spec/ruby/core/nil/to_i_spec.rb
@@ -5,7 +5,7 @@ describe "NilClass#to_i" do
     nil.to_i.should == 0
   end
 
-  it "does not cause NilClass to be coerced to Fixnum" do
+  it "does not cause NilClass to be coerced to Integer" do
     (0 == nil).should == false
   end
 end
diff --git a/spec/ruby/core/nil/to_s_spec.rb b/spec/ruby/core/nil/to_s_spec.rb
index 4b61f589f7..016ba4165a 100644
--- a/spec/ruby/core/nil/to_s_spec.rb
+++ b/spec/ruby/core/nil/to_s_spec.rb
@@ -5,13 +5,11 @@ describe "NilClass#to_s" do
     nil.to_s.should == ""
   end
 
-  ruby_version_is "2.7" do
-    it "returns a frozen string" do
-      nil.to_s.frozen?.should == true
-    end
+  it "returns a frozen string" do
+    nil.to_s.should.frozen?
+  end
 
-    it "always returns the same string" do
-      nil.to_s.should equal(nil.to_s)
-    end
+  it "always returns the same string" do
+    nil.to_s.should.equal?(nil.to_s)
   end
 end