Update to ruby/spec@a6b8805

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60525 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/ruby/.rubocop.yml

@@ -7,13 +7,28 @@ AllCops:
     - command_line/fixtures/bad_syntax.rb
   DisabledByDefault: true
 
+Layout/TrailingWhitespace:
+  Enabled: true
+
 Lint:
   Enabled: true
 
 Lint/AssignmentInCondition:
   Enabled: false
 
-Lint/LiteralInCondition:
+Lint/BooleanSymbol:
+  Enabled: false
+
+Lint/InterpolationCheck:
+  Enabled: false
+
+Lint/LiteralAsCondition:
+  Enabled: false
+
+Lint/UnneededRequireStatement:
+  Enabled: false
+
+Lint/RescueWithoutErrorClass:
   Enabled: false
 
 Lint/UnifiedInteger:
@@ -38,3 +53,7 @@ Lint/Void:
 Lint/EmptyExpression:
   Exclude:
     - 'language/**/*.rb'
+
+Lint/UriRegexp:
+  Exclude:
+    - 'library/uri/regexp_spec.rb'

spec/ruby/.rubocop_todo.yml

@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2017-06-18 19:12:38 +0200 using RuboCop version 0.49.1.
+# on 2017-10-09 20:22:01 +0200 using RuboCop version 0.50.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -52,7 +52,7 @@ Lint/FloatOutOfRange:
   Exclude:
     - 'core/string/modulo_spec.rb'
 
-# Offense count: 46
+# Offense count: 43
 Lint/FormatParameterMismatch:
   Exclude:
     - 'core/kernel/sprintf_spec.rb'
@@ -137,6 +137,7 @@ Lint/RescueException:
     - 'library/erb/filename_spec.rb'
 
 # Offense count: 1
+# Cop supports --auto-correct.
 Lint/ScriptPermission:
   Exclude:
     - 'command_line/fixtures/bin/launcher.rb'
@@ -181,7 +182,7 @@ Lint/UnneededSplatExpansion:
     - 'language/send_spec.rb'
     - 'language/variables_spec.rb'
 
-# Offense count: 53
+# Offense count: 55
 Lint/UnreachableCode:
   Exclude:
     - 'core/enumerator/lazy/fixtures/classes.rb'
@@ -198,7 +199,7 @@ Lint/UnreachableCode:
     - 'optional/capi/kernel_spec.rb'
     - 'shared/kernel/raise.rb'
 
-# Offense count: 9
+# Offense count: 7
 # Configuration parameters: ContextCreatingMethods, MethodCreatingMethods.
 Lint/UselessAccessModifier:
   Exclude:
@@ -206,6 +207,4 @@ Lint/UselessAccessModifier:
     - 'core/module/fixtures/classes.rb'
     - 'core/module/module_function_spec.rb'
     - 'core/module/private_class_method_spec.rb'
-    - 'core/module/private_spec.rb'
-    - 'core/module/protected_spec.rb'
-    - 'core/module/public_spec.rb'
+    - 'language/fixtures/send.rb'

spec/ruby/.travis.yml

@@ -3,21 +3,23 @@ language: ruby
 install:
   - git clone https://github.com/ruby/mspec.git ../mspec
 script:
-  - if [ -n "$RUBOCOP" ]; then gem install rubocop -v 0.49.1 && rubocop; fi
+  - if [ -n "$RUBOCOP" ]; then gem install rubocop -v 0.51.0 && rubocop; fi
   - ../mspec/bin/mspec $MSPEC_OPTS
 matrix:
   include:
     - os: osx
-      rvm: 2.4.0
+      osx_image: xcode9
+      rvm: 2.4.2
+      env: CHECK_LEAKS=true
     - os: linux
-      rvm: 2.4.1
+      rvm: 2.4.2
       env: MSPEC_OPTS="-R2 -ff"
     - os: linux
-      rvm: 2.2.7
+      rvm: 2.2.8
     - os: linux
-      rvm: 2.3.4
+      rvm: 2.3.5
     - os: linux
-      rvm: 2.4.1
+      rvm: 2.4.2
       env: CHECK_LEAKS=true RUBOCOP=true
     - os: linux
       rvm: ruby-head

spec/ruby/CONTRIBUTING.md

@@ -48,9 +48,116 @@ You might also want to search for:
 
 which indicates the file was generated but the method unspecified.
 
+### Matchers and expectations
+
+Here is a list of frequently-used matchers, which should be enough for most specs.
+There are a few extra specific matchers used in the couple specs that need it.
+
+```ruby
+(1 + 2).should == 3 # Calls #==
+(1 + 2).should_not == 5
+
+File.should equal(File) # Calls #equal? (tests identity)
+(1 + 2).should eql(3) # Calls #eql? (Hash equality)
+
+1.should < 2
+2.should <= 2
+3.should >= 3
+4.should > 3
+
+"Hello".should =~ /l{2}/ # Calls #=~ (Regexp match)
+
+[].should be_empty # Calls #empty?
+[1,2,3].should include(2) # Calls #include?
+
+(0.1 + 0.2).should be_close(0.3, TOLERANCE) # (0.2-0.1).abs < TOLERANCE
+(0.0/0.0).should be_nan # Calls Float#nan?
+(1.0/0.0).should be_positive_infinity
+(-1.0/0.0).should be_negative_infinity
+
+3.14.should be_an_instance_of(Float) # Calls #instance_of?
+3.14.should be_kind_of(Numeric) # Calls #is_a?
+Numeric.should be_ancestor_of(Float) # Float.ancestors.include?(Numeric)
+
+3.14.should respond_to(:to_i) # Calls #respond_to?
+Fixnum.should have_instance_method(:+)
+Array.should have_method(:new)
+# Also have_constant, have_private_instance_method, have_singleton_method, etc
+
+-> {
+  raise "oops"
+}.should raise_error(RuntimeError, /oops/)
+
+# To avoid! Instead, use an expectation testing what the code in the lambda does.
+# If an exception is raised, it will fail the example anyway.
+-> { ... }.should_not raise_error
+
+-> {
+  Fixnum
+}.should complain(/constant ::Fixnum is deprecated/) # Expect a warning
+```
+
 ### Guards
 
 Different guards are available as defined by mspec.
+Here is a list of the most commonly-used guards:
+
+```ruby
+ruby_version_is ""..."2.4" do
+  # Specs for RUBY_VERSION < 2.4
+end
+
+ruby_version_is "2.4" do
+  # Specs for RUBY_VERSION >= 2.4
+end
+
+platform_is :windows do
+  # Specs only valid on Windows
+end
+
+platform_is_not :windows do
+  # Specs valid on platforms other than Windows
+end
+
+platform_is :linux, :darwin do # OR
+end
+
+platform_is_not :linux, :darwin do # Not Linux and not Darwin
+end
+
+platform_is wordsize: 64 do
+  # 64-bit platform
+end
+
+big_endian do
+  # Big-endian platform
+end
+
+# In case there is a bug in MRI but the expected behavior is obvious
+# 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_bug '#13669', ''...'2.5' do
+  it "works like this" do
+    # Specify the expected behavior here, not the bug
+  end
+end
+
+
+# Combining guards
+guard -> { platform_is :windows and ruby_version_is ""..."2.3" } do
+  # Windows and RUBY_VERSION < 2.3
+end
+
+guard_not -> { platform_is :windows and ruby_version_is ""..."2.3" } do
+  # The opposite
+end
+
+# Custom guard
+max_uint = (1 << 32) - 1
+guard -> { max_uint <= fixnum_max } do
+end
+```
+
 In general, the usage of guards should be minimized as possible.
 
 There are no guards to define implementation-specific behavior because

spec/ruby/core/array/at_spec.rb

@@ -15,7 +15,7 @@ describe "Array#at" do
     a.at(7).should == nil
   end
 
-  it "returns the (-n)'th elemet from the last, for the given negative index n" do
+  it "returns the (-n)'th element from the last, for the given negative index n" do
     a = [1, 2, 3, 4, 5, 6]
     a.at(-1).should == 6
     a.at(-2).should == 5
@@ -50,7 +50,7 @@ describe "Array#at" do
     lambda { [].at("cat") }.should raise_error(TypeError)
   end
 
-  it "raises an ArgumentError when 2 or more arguments is passed" do
+  it "raises an ArgumentError when 2 or more arguments are passed" do
     lambda { [:a, :b].at(0,1) }.should raise_error(ArgumentError)
   end
 end

spec/ruby/core/array/intersection_spec.rb

@@ -19,7 +19,7 @@ describe "Array#&" do
 
   it "does not modify the original Array" do
     a = [1, 1, 3, 5]
-    a & [1, 2, 3]
+    (a & [1, 2, 3]).should == [1, 3]
     a.should == [1, 1, 3, 5]
   end
 
@@ -52,7 +52,7 @@ describe "Array#&" do
     obj1.stub!(:hash).and_return(0)
     obj2.stub!(:hash).and_return(0)
     obj1.should_receive(:eql?).at_least(1).and_return(true)
-    obj2.should_receive(:eql?).at_least(1).and_return(true)
+    obj2.stub!(:eql?).and_return(true)
 
     ([obj1] & [obj2]).should == [obj1]
     ([obj1, obj1, obj2, obj2] & [obj2]).should == [obj1]

spec/ruby/core/array/max_spec.rb

@@ -1,6 +1,12 @@
 require File.expand_path('../../../spec_helper', __FILE__)
 
 describe "Array#max" do
+  ruby_version_is "2.4" do
+    it "is defined on Array" do
+      [1].method(:max).owner.should equal Array
+    end
+  end
+
   it "returns nil with no values" do
     [].max.should == nil
   end

spec/ruby/core/array/min_spec.rb

@@ -1,6 +1,12 @@
 require File.expand_path('../../../spec_helper', __FILE__)
 
 describe "Array#min" do
+  ruby_version_is "2.4" do
+    it "is defined on Array" do
+      [1].method(:max).owner.should equal Array
+    end
+  end
+
   it "returns nil with no values" do
     [].min.should == nil
   end

spec/ruby/core/array/pack/buffer_spec.rb

@@ -0,0 +1,52 @@
+# encoding: ascii-8bit
+
+require File.expand_path('../../../../spec_helper', __FILE__)
+
+ruby_version_is '2.4' do
+  describe "Aray#pack with `buffer` option" do
+    it "returns specified buffer" do
+      n = [ 65, 66, 67 ]
+      buffer = " "*3
+      result = n.pack("ccc", buffer: buffer)      #=> "ABC"
+      result.should equal(buffer)
+    end
+
+    it "adds result at the end of buffer content" do
+      n = [ 65, 66, 67 ] # result without buffer is "ABC"
+
+      buffer = ""
+      n.pack("ccc", buffer: buffer).should == "ABC"
+
+      buffer = "123"
+      n.pack("ccc", buffer: buffer).should == "123ABC"
+
+      buffer = "12345"
+      n.pack("ccc", buffer: buffer).should == "12345ABC"
+    end
+
+    it "raises TypeError exception if buffer is not String" do
+      lambda { [65].pack("ccc", buffer: []) }.should raise_error(
+        TypeError, "buffer must be String, not Array")
+    end
+
+    context "offset (@) is specified" do
+      it 'keeps buffer content if it is longer than offset' do
+        n = [ 65, 66, 67 ]
+        buffer = "123456"
+        n.pack("@3ccc", buffer: buffer).should == "123ABC"
+      end
+
+      it "fills the gap with \0 if buffer content is shorter than offset" do
+        n = [ 65, 66, 67 ]
+        buffer = "123"
+        n.pack("@6ccc", buffer: buffer).should == "123\0\0\0ABC"
+      end
+
+      it 'does not keep buffer content if it is longer than offset + result' do
+        n = [ 65, 66, 67 ]
+        buffer = "1234567890"
+        n.pack("@3ccc", buffer: buffer).should == "123ABC"
+      end
+    end
+  end
+end

spec/ruby/core/array/permutation_spec.rb

@@ -52,7 +52,7 @@ describe "Array#permutation" do
   end
 
   it "returns no permutations when the given length has no permutations" do
-    @numbers.permutation(9).entries.size == 0
+    @numbers.permutation(9).entries.size.should == 0
     @numbers.permutation(9) { |n| @yielded << n }
     @yielded.should == []
   end

spec/ruby/core/array/pop_spec.rb

@@ -119,7 +119,7 @@ describe "Array#pop" do
       a.should == []
     end
 
-    it "raises a TypeError when the passed n can be coerced to Integer" do
+    it "raises a TypeError when the passed n cannot be coerced to Integer" do
       lambda{ [1, 2].pop("cat") }.should raise_error(TypeError)
       lambda{ [1, 2].pop(nil) }.should raise_error(TypeError)
     end

spec/ruby/core/array/shift_spec.rb

@@ -104,7 +104,7 @@ describe "Array#shift" do
       a.should == []
     end
 
-    it "raises a TypeError when the passed n can be coerced to Integer" do
+    it "raises a TypeError when the passed n cannot be coerced to Integer" do
       lambda{ [1, 2].shift("cat") }.should raise_error(TypeError)
       lambda{ [1, 2].shift(nil) }.should raise_error(TypeError)
     end

spec/ruby/core/array/sum_spec.rb

@@ -0,0 +1,44 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is '2.4' do
+  describe "Array#sum" do
+    it "returns the sum of elements" do
+      [1, 2, 3].sum.should == 6
+    end
+
+    it "applies a block to each element before adding if it's given" do
+      [1, 2, 3].sum { |i| i * 10 }.should == 60
+    end
+
+    it "returns init value if array is empty" do
+      [].sum(-1).should == -1
+    end
+
+    it "returns 0 if array is empty and init is omitted" do
+      [].sum.should == 0
+    end
+
+    it "adds init value to the sum of elemens" do
+      [1, 2, 3].sum(10).should == 16
+    end
+
+    it "can be used for non-numeric objects by providing init value" do
+      ["a", "b", "c"].sum("").should == "abc"
+    end
+
+    it 'raises TypeError if any element are not numeric' do
+      lambda { ["a"].sum }.should raise_error(TypeError)
+    end
+
+    it 'raises TypeError if any element cannot be added to init value' do
+      lambda { [1].sum([]) }.should raise_error(TypeError)
+    end
+
+    it "calls + to sum the elements" do
+      a = mock("a")
+      b = mock("b")
+      a.should_receive(:+).with(b).and_return(42)
+      [b].sum(a).should == 42
+    end
+  end
+end

spec/ruby/core/bignum/bignum_spec.rb

@@ -16,4 +16,16 @@ describe "Bignum" do
       Bignum.new
     end.should raise_error(NoMethodError)
   end
+
+  ruby_version_is '2.4' do
+    it "unified into Integer" do
+      Bignum.should equal(Integer)
+    end
+
+    it "is deprecated" do
+      -> {
+        Bignum
+      }.should complain(/constant ::Bignum is deprecated/)
+    end
+  end
 end

spec/ruby/core/complex/finite_spec.rb

@@ -0,0 +1,36 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is "2.4" do
+  describe "Complex#finite?" do
+    it "returns true if magnitude is finite" do
+      (1+1i).finite?.should == true
+    end
+
+    it "returns false for positive infinity" do
+      value = Complex(Float::INFINITY, 42)
+      value.finite?.should == false
+    end
+
+    it "returns false for positive complex with infinite imaginary" do
+      value = Complex(1, Float::INFINITY)
+      value.finite?.should == false
+    end
+
+    it "returns false for negative infinity" do
+      value = -Complex(Float::INFINITY, 42)
+      value.finite?.should == false
+    end
+
+    it "returns false for negative complex with infinite imaginary" do
+      value = -Complex(1, Float::INFINITY)
+      value.finite?.should == false
+    end
+
+    ruby_bug "#14014", "2.4"..."2.5" do
+      it "returns false for NaN" do
+        value = Complex(Float::NAN, Float::NAN)
+        value.finite?.should == false
+      end
+    end
+  end
+end

spec/ruby/core/complex/infinite_spec.rb

@@ -0,0 +1,34 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is "2.4" do
+  describe "Complex#infinite?" do
+    it "returns nil if magnitude is finite" do
+      (1+1i).infinite?.should == nil
+    end
+
+    it "returns 1 for positive infinity" do
+      value = Complex(Float::INFINITY, 42).infinite?
+      value.should == 1
+    end
+
+    it "returns 1 for positive complex with infinite imaginary" do
+      value = Complex(1, Float::INFINITY).infinite?
+      value.should == 1
+    end
+
+    it "returns -1 for negative infinity" do
+      value = -Complex(Float::INFINITY, 42).infinite?
+      value.should == -1
+    end
+
+    it "returns -1 for negative complex with infinite imaginary" do
+      value = -Complex(1, Float::INFINITY).infinite?
+      value.should == -1
+    end
+
+    it "returns nil for NaN" do
+      value = Complex(0, Float::NAN).infinite?
+      value.should == nil
+    end
+  end
+end

spec/ruby/core/dir/empty_spec.rb

@@ -0,0 +1,33 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is "2.4" do
+  describe "Dir.empty?" do
+    before :all do
+      @empty_dir = tmp("empty_dir")
+      mkdir_p @empty_dir
+    end
+
+    after :all do
+      rm_r @empty_dir
+    end
+
+    it "returns true for empty directories" do
+      result = Dir.empty? @empty_dir
+      result.should be_true
+    end
+
+    it "returns false for non-empty directories" do
+      result = Dir.empty? __dir__
+      result.should be_false
+    end
+
+    it "returns false for a non-directory" do
+      result = Dir.empty? __FILE__
+      result.should be_false
+    end
+
+    it "raises ENOENT for nonexistent directories" do
+      lambda { Dir.empty? tmp("nonexistent") }.should raise_error(Errno::ENOENT)
+    end
+  end
+end

spec/ruby/core/dir/glob_spec.rb

@@ -68,7 +68,7 @@ describe "Dir.glob" do
     Dir.glob('**/', File::FNM_DOTMATCH).sort.should == expected
   end
 
-  # This is a seperate case to check **/ coming after a constant
+  # This is a separate case to check **/ coming after a constant
   # directory as well.
   it "recursively matches any subdirectories except './' or '../' with '**/' and option File::FNM_DOTMATCH" do
     expected = %w[

spec/ruby/core/encoding/converter/primitive_convert_spec.rb

@@ -89,7 +89,7 @@ with_feature :encoding do
       @ec.primitive_convert("","",nil,nil, {after_output: true}).should == :finished
     end
 
-    it "sets the destination buffer's encoding to the destination encoding if the conversion suceeded" do
+    it "sets the destination buffer's encoding to the destination encoding if the conversion succeeded" do
       dest = "".force_encoding('utf-8')
       dest.encoding.should == Encoding::UTF_8
       @ec.primitive_convert("\u{98}",dest).should == :finished

spec/ruby/core/encoding/converter/primitive_errinfo_spec.rb

@@ -16,15 +16,13 @@ with_feature :encoding do
 
     it "returns [:source_buffer_empty,nil,nil,nil, nil] when #convert last succeeded" do
       ec = Encoding::Converter.new('ascii','utf-8')
-      ec.convert("a".force_encoding('ascii')).should == "a".\
-        force_encoding('utf-8')
+      ec.convert("a".force_encoding('ascii')).should == "a".force_encoding('utf-8')
       ec.primitive_errinfo.should == [:source_buffer_empty, nil, nil, nil, nil]
     end
 
     it "returns [:destination_buffer_full,nil,nil,nil,nil] when #primitive_convert last returned :destination_buffer_full" do
       ec = Encoding::Converter.new("utf-8", "iso-2022-jp")
-      ec.primitive_convert("\u{9999}", "", 0, 0, partial_input: false) \
-        .should == :destination_buffer_full
+      ec.primitive_convert("\u{9999}", "", 0, 0, partial_input: false).should == :destination_buffer_full
       ec.primitive_errinfo.should == [:destination_buffer_full, nil, nil, nil, nil]
     end
 

spec/ruby/core/encoding/converter/putback_spec.rb

@@ -40,8 +40,7 @@ with_feature :encoding do
       src = "\x00\xd8\x61\x00"
       dst = ""
       ec.primitive_convert(src, dst).should == :invalid_byte_sequence
-      ec.primitive_errinfo.should ==
-        [:invalid_byte_sequence, "UTF-16LE", "UTF-8", "\x00\xD8", "a\x00"]
+      ec.primitive_errinfo.should == [:invalid_byte_sequence, "UTF-16LE", "UTF-8", "\x00\xD8", "a\x00"]
       ec.putback(1).should == "\x00".force_encoding("utf-16le")
       ec.putback.should == "a".force_encoding("utf-16le")
       ec.putback.should == ""

spec/ruby/core/encoding/invalid_byte_sequence_error/source_encoding_name_spec.rb

@@ -23,7 +23,7 @@ with_feature :encoding do
     # conversion from ISO-8859-1 -> UTF-8 succeeded, but the conversion from
     # UTF-8 to EUC-JP failed. IOW, it failed when the source encoding was
     # UTF-8, so UTF-8 is regarded as the source encoding.
-    it "is equal to the source encoding at the stage of the conversion path where the error occured" do
+    it "is equal to the source encoding at the stage of the conversion path where the error occurred" do
       @exception2.source_encoding_name.should == 'UTF-8'
     end
   end

spec/ruby/core/encoding/invalid_byte_sequence_error/source_encoding_spec.rb

@@ -28,7 +28,7 @@ with_feature :encoding do
 
     # FIXME: Derive example where the failure occurs at the UTF-8 ->
     # ISO-8859-1 case so as to better illustrate the issue
-    it "is equal to the source encoding at the stage of the conversion path where the error occured" do
+    it "is equal to the source encoding at the stage of the conversion path where the error occurred" do
       @exception2.source_encoding.should == Encoding::EUC_JP
     end
   end

spec/ruby/core/encoding/undefined_conversion_error/source_encoding_name_spec.rb

@@ -23,7 +23,7 @@ with_feature :encoding do
     # conversion from ISO-8859-1 -> UTF-8 succeeded, but the conversion from
     # UTF-8 to EUC-JP failed. IOW, it failed when the source encoding was
     # UTF-8, so UTF-8 is regarded as the source encoding.
-    it "is equal to the source encoding at the stage of the conversion path where the error occured" do
+    it "is equal to the source encoding at the stage of the conversion path where the error occurred" do
       @exception2.source_encoding_name.should == 'UTF-8'
     end
   end

spec/ruby/core/encoding/undefined_conversion_error/source_encoding_spec.rb

@@ -24,7 +24,7 @@ with_feature :encoding do
     # conversion from ISO-8859-1 -> UTF-8 succeeded, but the conversion from
     # UTF-8 to EUC-JP failed. IOW, it failed when the source encoding was
     # UTF-8, so UTF-8 is regarded as the source encoding.
-    it "is equal to the source encoding at the stage of the conversion path where the error occured" do
+    it "is equal to the source encoding at the stage of the conversion path where the error occurred" do
       @exception2.source_encoding.should == Encoding::UTF_8
     end
   end

spec/ruby/core/enumerable/any_spec.rb

@@ -68,11 +68,11 @@ describe "Enumerable#any?" do
 
   describe "with block" do
     it "returns true if the block ever returns other than false or nil" do
-      @enum.any? { true } == true
-      @enum.any? { 0 } == true
-      @enum.any? { 1 } == true
+      @enum.any? { true }.should == true
+      @enum.any? { 0 }.should == true
+      @enum.any? { 1 }.should == true
 
-      @enum1.any? { Object.new } == true
+      @enum1.any? { Object.new }.should == true
       @enum1.any?{ |o| o < 1 }.should == true
       @enum1.any?{ |o| 5 }.should == true
 

spec/ruby/core/enumerable/cycle_spec.rb

@@ -69,7 +69,7 @@ describe "Enumerable#cycle" do
       enum.cycle(obj).to_a.should == [3, 2, 1, 3, 2, 1]
     end
 
-    it "raises a TypeError when the passed n can be coerced to Integer" do
+    it "raises a TypeError when the passed n cannot be coerced to Integer" do
       enum = EnumerableSpecs::Numerous.new
       lambda{ enum.cycle("cat"){} }.should raise_error(TypeError)
     end

spec/ruby/core/enumerable/drop_spec.rb

@@ -34,7 +34,7 @@ describe "Enumerable#drop" do
       EnumerableSpecs::Numerous.new(3, 2, 1, :go).drop(4).should == []
     end
 
-    it "raises a TypeError when the passed n can be coerced to Integer" do
+    it "raises a TypeError when the passed n cannot be coerced to Integer" do
       lambda{ @enum.drop("hat") }.should raise_error(TypeError)
       lambda{ @enum.drop(nil) }.should raise_error(TypeError)
     end

spec/ruby/core/enumerable/uniq_spec.rb

@@ -7,6 +7,71 @@ ruby_version_is '2.4' do
       [0, 1, 2, 3].to_enum.uniq { |n| n.even? }.should == [0, 1]
     end
 
+    it "uses eql? semantics" do
+      [1.0, 1].to_enum.uniq.should == [1.0, 1]
+    end
+
+    it "compares elements first with hash" do
+      x = mock('0')
+      x.should_receive(:hash).at_least(1).and_return(0)
+      y = mock('0')
+      y.should_receive(:hash).at_least(1).and_return(0)
+
+      [x, y].to_enum.uniq.should == [x, y]
+    end
+
+    it "does not compare elements with different hash codes via eql?" do
+      x = mock('0')
+      x.should_not_receive(:eql?)
+      y = mock('1')
+      y.should_not_receive(:eql?)
+
+      x.should_receive(:hash).at_least(1).and_return(0)
+      y.should_receive(:hash).at_least(1).and_return(1)
+
+      [x, y].to_enum.uniq.should == [x, y]
+    end
+
+    it "compares elements with matching hash codes with #eql?" do
+      a = Array.new(2) do
+        obj = mock('0')
+        obj.should_receive(:hash).at_least(1).and_return(0)
+
+        def obj.eql?(o)
+          # It's undefined whether the impl does a[0].eql?(a[1]) or
+          # a[1].eql?(a[0]) so we taint both.
+          taint
+          o.taint
+          false
+        end
+
+        obj
+      end
+
+      a.uniq.should == a
+      a[0].tainted?.should == true
+      a[1].tainted?.should == true
+
+      a = Array.new(2) do
+        obj = mock('0')
+        obj.should_receive(:hash).at_least(1).and_return(0)
+
+        def obj.eql?(o)
+          # It's undefined whether the impl does a[0].eql?(a[1]) or
+          # a[1].eql?(a[0]) so we taint both.
+          taint
+          o.taint
+          true
+        end
+
+        obj
+      end
+
+      a.to_enum.uniq.size.should == 1
+      a[0].tainted?.should == true
+      a[1].tainted?.should == true
+    end
+
     context 'when yielded with multiple arguments' do
       before :each do
         @enum = Object.new.to_enum

spec/ruby/core/enumerator/lazy/force_spec.rb

@@ -24,7 +24,7 @@ describe "Enumerator::Lazy#force" do
       (0..Float::INFINITY).lazy.map(&:succ).take(2).force.should == [1, 2]
 
       @eventsmixed.take(1).map(&:succ).force.should == [1]
-      ScratchPad.recorded == [:after_yields]
+      ScratchPad.recorded.should == [:before_yield]
     end
   end
 end

spec/ruby/core/false/dup_spec.rb

@@ -0,0 +1,9 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is '2.4' do
+  describe "FalseClass#dup" do
+    it "returns self" do
+      false.dup.should equal(false)
+    end
+  end
+end

spec/ruby/core/file/empty_spec.rb

@@ -0,0 +1,15 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../../../shared/file/zero', __FILE__)
+
+describe "File.empty?" do
+  ruby_version_is "2.4" do
+    it_behaves_like :file_zero, :empty?, File
+    it_behaves_like :file_zero_missing, :empty?, File
+
+    platform_is :solaris do
+      it "returns false for /dev/null" do
+        File.empty?('/dev/null').should == true
+      end
+    end
+  end
+end

spec/ruby/core/file/readlink_spec.rb

@@ -3,7 +3,7 @@ require File.expand_path('../../../spec_helper', __FILE__)
 describe "File.readlink" do
   # symlink/readlink are not supported on Windows
   platform_is_not :windows do
-    describe "File.readlink with absolute paths" do
+    describe "with absolute paths" do
       before :each do
         @file = tmp('file_readlink.txt')
         @link = tmp('file_readlink.lnk')
@@ -35,7 +35,26 @@ describe "File.readlink" do
       end
     end
 
-    describe "File.readlink when changing the working directory" do
+    describe "with paths containing unicode characters" do
+      before :each do
+        @file = tmp('tàrget.txt')
+        @link = tmp('lïnk.lnk')
+        File.symlink(@file, @link)
+      end
+
+      after :each do
+        rm_r @file, @link
+      end
+
+      it "returns the name of the file referenced by the given link" do
+        touch @file
+        result = File.readlink(@link)
+        result.encoding.should equal Encoding.find('filesystem')
+        result.should == @file.dup.force_encoding(Encoding.find('filesystem'))
+      end
+    end
+
+    describe "when changing the working directory" do
       before :each do
         @cwd = Dir.pwd
         @tmpdir = tmp("/readlink")

spec/ruby/core/file/shared/fnmatch.rb

@@ -75,11 +75,11 @@ describe :file_fnmatch, shared: true do
     File.send(@method, 'c*t', 'c/a/b/t').should == true
   end
 
-  it "matches ranges of characters using bracket expresions (e.g. [a-z])" do
+  it "matches ranges of characters using bracket expression (e.g. [a-z])" do
     File.send(@method, 'ca[a-z]', 'cat').should == true
   end
 
-  it "matches ranges of characters using bracket expresions, taking case into account" do
+  it "matches ranges of characters using bracket expression, taking case into account" do
     File.send(@method, '[a-z]', 'D').should == false
     File.send(@method, '[^a-z]', 'D').should == true
     File.send(@method, '[A-Z]', 'd').should == false
@@ -92,7 +92,7 @@ describe :file_fnmatch, shared: true do
     File.send(@method, '/ca[s][s-t]/rul[a-b]/[z]he/[x-Z]orld', '/cats/rule/the/World').should == false
   end
 
-  it "matches ranges of characters using exclusive bracket expresions (e.g. [^t] or [!t])" do
+  it "matches ranges of characters using exclusive bracket expression (e.g. [^t] or [!t])" do
     File.send(@method, 'ca[^t]', 'cat').should == false
     File.send(@method, 'ca[!t]', 'cat').should == false
   end
@@ -106,13 +106,13 @@ describe :file_fnmatch, shared: true do
   end
 
   platform_is_not :windows do
-    it "doesn't match case sensitive characters on platfroms with case sensitive paths, when flags include FNM_SYSCASE" do
+    it "doesn't match case sensitive characters on platforms with case sensitive paths, when flags include FNM_SYSCASE" do
       File.send(@method, 'cat', 'CAT', File::FNM_SYSCASE).should == false
     end
   end
 
   platform_is :windows do
-    it "matches case sensitive characters on platfroms with case insensitive paths, when flags include FNM_SYSCASE" do
+    it "matches case sensitive characters on platforms with case insensitive paths, when flags include FNM_SYSCASE" do
       File.send(@method, 'cat', 'CAT', File::FNM_SYSCASE).should == true
     end
   end

spec/ruby/core/fixnum/fixnum_spec.rb

@@ -16,4 +16,16 @@ describe "Fixnum" do
       Fixnum.new
     end.should raise_error(NoMethodError)
   end
+
+  ruby_version_is '2.4' do
+    it "is unified into Integer" do
+      Fixnum.should equal(Integer)
+    end
+
+    it "is deprecated" do
+      -> {
+        Fixnum
+      }.should complain(/constant ::Fixnum is deprecated/)
+    end
+  end
 end

spec/ruby/core/float/ceil_spec.rb

@@ -10,4 +10,14 @@ describe "Float#ceil" do
     -9223372036854775808.1.ceil.should eql(-9223372036854775808)
     +9223372036854775808.1.ceil.should eql(+9223372036854775808)
   end
+
+  ruby_version_is "2.4" do
+    it "returns the smallest number greater than or equal to self with an optionally given precision" do
+      2.1679.ceil(0).should   eql(3)
+      214.94.ceil(-1).should  eql(220)
+      7.0.ceil(1).should      eql(7.0)
+      -1.234.ceil(2).should   eql(-1.23)
+      5.123812.ceil(4).should eql(5.1239)
+    end
+  end
 end

spec/ruby/core/float/dup_spec.rb

@@ -0,0 +1,10 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is '2.4' do
+  describe "Float#dup" do
+    it "returns self" do
+      float = 2.4
+      float.dup.should equal(float)
+    end
+  end
+end

spec/ruby/core/float/floor_spec.rb

@@ -10,4 +10,14 @@ describe "Float#floor" do
     -9223372036854775808.1.floor.should eql(-9223372036854775808)
     +9223372036854775808.1.floor.should eql(+9223372036854775808)
   end
+
+  ruby_version_is "2.4" do
+    it "returns the largest number less than or equal to self with an optionally given precision" do
+      2.1679.floor(0).should   eql(2)
+      214.94.floor(-1).should  eql(210)
+      7.0.floor(1).should      eql(7.0)
+      -1.234.floor(2).should   eql(-1.24)
+      5.123812.floor(4).should eql(5.1238)
+    end
+  end
 end

spec/ruby/core/float/round_spec.rb

@@ -84,4 +84,18 @@ describe "Float#round" do
     -2.5e200.round(-200).should eql( -3 * 10 ** 200 )
     -2.4e200.round(-200).should eql( -2 * 10 ** 200 )
   end
+
+  ruby_version_is "2.4" do
+    it "returns different rounded values depending on the half option" do
+      2.5.round(half: :up).should      eql(3)
+      2.5.round(half: :down).should    eql(2)
+      2.5.round(half: :even).should    eql(2)
+      3.5.round(half: :up).should      eql(4)
+      3.5.round(half: :down).should    eql(3)
+      3.5.round(half: :even).should    eql(4)
+      (-2.5).round(half: :up).should   eql(-3)
+      (-2.5).round(half: :down).should eql(-2)
+      (-2.5).round(half: :even).should eql(-2)
+    end
+  end
 end

spec/ruby/core/float/truncate_spec.rb

@@ -3,4 +3,14 @@ require File.expand_path('../shared/to_i', __FILE__)
 
 describe "Float#truncate" do
   it_behaves_like(:float_to_i, :truncate)
+
+  ruby_version_is "2.4" do
+    it "returns self truncated to an optionally given precision" do
+      2.1679.truncate(0).should   eql(2)
+      7.1.truncate(1).should      eql(7.1)
+      214.94.truncate(-1).should  eql(210)
+      -1.234.truncate(2).should   eql(-1.23)
+      5.123812.truncate(4).should eql(5.1238)
+    end
+  end
 end

spec/ruby/core/hash/delete_spec.rb

@@ -11,13 +11,13 @@ describe "Hash#delete" do
   it "calls supplied block if the key is not found" do
     { a: 1, b: 10, c: 100 }.delete(:d) { 5 }.should == 5
     Hash.new(:default).delete(:d) { 5 }.should == 5
-    Hash.new { :defualt }.delete(:d) { 5 }.should == 5
+    Hash.new { :default }.delete(:d) { 5 }.should == 5
   end
 
   it "returns nil if the key is not found when no block is given" do
     { a: 1, b: 10, c: 100 }.delete(:d).should == nil
     Hash.new(:default).delete(:d).should == nil
-    Hash.new { :defualt }.delete(:d).should == nil
+    Hash.new { :default }.delete(:d).should == nil
   end
 
   # MRI explicitly implements this behavior

spec/ruby/core/hash/transform_values_spec.rb

@@ -24,6 +24,15 @@ ruby_version_is "2.4" do
         enumerator.each(&:succ).should == { a: 2, b: 3, c: 4 }
       end
     end
+
+    it "returns a Hash instance, even on subclasses" do
+      klass = Class.new(Hash)
+      h = klass.new
+      h[:foo] = 42
+      r = h.transform_values{|v| 2 * v}
+      r[:foo].should == 84
+      r.class.should == Hash
+    end
   end
 
   describe "Hash#transform_values!" do
@@ -41,6 +50,14 @@ ruby_version_is "2.4" do
       @hash.should ==  { a: 2, b: 3, c: 4 }
     end
 
+    it "partially modifies the contents if we broke from the block" do
+      @hash.transform_values! do |v|
+        break if v == 3
+        100 + v
+      end
+      @hash.should == { a: 101, b: 102, c: 3}
+    end
+
     context "when no block is given" do
       it "returns a sized Enumerator" do
         enumerator = @hash.transform_values!
@@ -56,6 +73,10 @@ ruby_version_is "2.4" do
         @hash.freeze
       end
 
+      it "raises a RuntimeError on an empty hash" do
+        ->{ {}.freeze.transform_values!(&:succ) }.should raise_error(RuntimeError)
+      end
+
       it "keeps pairs and raises a RuntimeError" do
         ->{ @hash.transform_values!(&:succ) }.should raise_error(RuntimeError)
         @hash.should == @initial_pairs

spec/ruby/core/integer/ceil_spec.rb

@@ -1,6 +1,21 @@
 require File.expand_path('../../../spec_helper', __FILE__)
 require File.expand_path('../shared/to_i', __FILE__)
+require File.expand_path('../shared/integer_rounding', __FILE__)
 
 describe "Integer#ceil" do
   it_behaves_like(:integer_to_i, :ceil)
+  it_behaves_like(:integer_rounding_positive_precision, :ceil)
+
+  ruby_version_is "2.4" do
+    context "precision argument specified as part of the ceil method is negative" do
+      it "returns the smallest integer greater than self with at least precision.abs trailing zeros" do
+        18.ceil(-1).should eql(20)
+        18.ceil(-2).should eql(100)
+        18.ceil(-3).should eql(1000)
+        -1832.ceil(-1).should eql(-1830)
+        -1832.ceil(-2).should eql(-1800)
+        -1832.ceil(-3).should eql(-1000)
+      end
+    end
+  end
 end

spec/ruby/core/integer/digits_spec.rb

@@ -0,0 +1,34 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is "2.4" do
+  describe "Integer#digits" do
+    it "returns an array of place values in base-10 by default" do
+      12345.digits.should == [5,4,3,2,1]
+    end
+
+    it "returns digits by place value of a given radix" do
+      12345.digits(7).should == [4,6,6,0,5]
+    end
+
+    it "converts the radix with #to_int" do
+      12345.digits(mock_int(2)).should == [1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1]
+    end
+
+    it "returns [0] when called on 0, regardless of base" do
+      0.digits.should == [0]
+      0.digits(7).should == [0]
+    end
+
+    it "raises ArgumentError when calling with a radix less than 2" do
+      lambda { 12345.digits(1) }.should raise_error(ArgumentError)
+    end
+
+    it "raises ArgumentError when calling with a negative radix" do
+      lambda { 12345.digits(-2) }.should raise_error(ArgumentError)
+    end
+
+    it "raises Math::DomainError when calling digits on a negative number" do
+      lambda { -12345.digits(7) }.should raise_error(Math::DomainError)
+    end
+  end
+end

spec/ruby/core/integer/dup_spec.rb

@@ -0,0 +1,10 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is '2.4' do
+  describe "Integer#dup" do
+    it "returns self" do
+      int = 2
+      int.dup.should equal(int)
+    end
+  end
+end

spec/ruby/core/integer/floor_spec.rb

@@ -1,6 +1,21 @@
 require File.expand_path('../../../spec_helper', __FILE__)
 require File.expand_path('../shared/to_i', __FILE__)
+require File.expand_path('../shared/integer_rounding', __FILE__)
 
 describe "Integer#floor" do
   it_behaves_like(:integer_to_i, :floor)
+  it_behaves_like(:integer_rounding_positive_precision, :floor)
+
+  ruby_version_is "2.4" do
+    context "precision argument specified as part of the floor method is negative" do
+      it "returns the largest integer less than self with at least precision.abs trailing zeros" do
+        1832.floor(-1).should eql(1830)
+        1832.floor(-2).should eql(1800)
+        1832.floor(-3).should eql(1000)
+        -1832.floor(-1).should eql(-1840)
+        -1832.floor(-2).should eql(-1900)
+        -1832.floor(-3).should eql(-2000)
+      end
+    end
+  end
 end

spec/ruby/core/integer/integer_spec.rb

@@ -4,6 +4,13 @@ describe "Integer" do
   it "includes Comparable" do
     Integer.include?(Comparable).should == true
   end
+
+  ruby_version_is "2.4" do
+    it "is the class of both small and large integers" do
+      42.class.should equal(Integer)
+      bignum_value.class.should equal(Integer)
+    end
+  end
 end
 
 describe "Integer#integer?" do

spec/ruby/core/integer/round_spec.rb

@@ -1,10 +1,12 @@
 require File.expand_path('../../../spec_helper', __FILE__)
 require File.expand_path('../shared/to_i', __FILE__)
+require File.expand_path('../shared/integer_rounding', __FILE__)
 
 describe "Integer#round" do
   it_behaves_like(:integer_to_i, :round)
+  it_behaves_like(:integer_rounding_positive_precision, :round)
 
-  ruby_version_is ""..."2.5" do
+  ruby_version_is ""..."2.5" do # Not just since 2.4
     it "rounds itself as a float if passed a positive precision" do
       [2, -4, 10**70, -10**100].each do |v|
         v.round(42).should eql(v.to_f)
@@ -12,20 +14,6 @@ describe "Integer#round" do
     end
   end
 
-  ruby_version_is "2.5" do
-    it "returns itself if passed a positive precision" do
-      [2, -4, 10**70, -10**100].each do |v|
-        v.round(42).should eql(v)
-      end
-    end
-  end
-
-  it "returns itself if passed zero" do
-    [2, -4, 10**70, -10**100].each do |v|
-      v.round(0).should eql(v)
-    end
-  end
-
   # redmine:5228
   it "returns itself rounded if passed a negative value" do
     +249.round(-2).should eql(+200)
@@ -74,4 +62,34 @@ describe "Integer#round" do
     obj.stub!(:to_int).and_return([])
     lambda { 42.round(obj) }.should raise_error(TypeError)
   end
+
+  ruby_version_is "2.4" do
+    it "returns different rounded values depending on the half option" do
+      25.round(-1, half: :up).should      eql(30)
+      25.round(-1, half: :down).should    eql(20)
+      25.round(-1, half: :even).should    eql(20)
+      35.round(-1, half: :up).should      eql(40)
+      35.round(-1, half: :down).should    eql(30)
+      35.round(-1, half: :even).should    eql(40)
+      (-25).round(-1, half: :up).should   eql(-30)
+      (-25).round(-1, half: :down).should eql(-20)
+      (-25).round(-1, half: :even).should eql(-20)
+    end
+  end
+
+  ruby_version_is "2.4"..."2.5" do
+    it "returns itself as a float if passed a positive precision and the half option" do
+      35.round(1, half: :up).should      eql(35.0)
+      35.round(1, half: :down).should    eql(35.0)
+      35.round(1, half: :even).should    eql(35.0)
+    end
+  end
+
+  ruby_version_is "2.5" do
+    it "returns itself if passed a positive precision and the half option" do
+      35.round(1, half: :up).should      eql(35)
+      35.round(1, half: :down).should    eql(35)
+      35.round(1, half: :even).should    eql(35)
+    end
+  end
 end

spec/ruby/core/integer/shared/integer_rounding.rb

@@ -0,0 +1,31 @@
+describe :integer_rounding_positive_precision, shared: true do
+  it "returns self if not passed a precision" do
+    [2, -4, 10**70, -10**100].each do |v|
+      v.send(@method).should eql(v)
+    end
+  end
+
+  ruby_version_is "2.4" do
+    it "returns self if passed a precision of zero" do
+      [2, -4, 10**70, -10**100].each do |v|
+        v.send(@method, 0).should eql(v)
+      end
+    end
+  end
+
+  ruby_version_is "2.4"..."2.5" do
+    it "returns itself as a float if passed a positive precision" do
+      [2, -4, 10**70, -10**100].each do |v|
+        v.send(@method, 42).should eql(v.to_f)
+      end
+    end
+  end
+
+  ruby_version_is "2.5" do
+    it "returns itself if passed a positive precision" do
+      [2, -4, 10**70, -10**100].each do |v|
+        v.send(@method, 42).should eql(v)
+      end
+    end
+  end
+end

spec/ruby/core/integer/sqrt_spec.rb

@@ -0,0 +1,33 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is "2.5" do
+  describe "Integer.sqrt" do
+    it "returns an integer" do
+      Integer.sqrt(10).should be_kind_of(Integer)
+    end
+
+    it "returns the integer square root of the argument" do
+      Integer.sqrt(0).should == 0
+      Integer.sqrt(1).should == 1
+      Integer.sqrt(24).should == 4
+      Integer.sqrt(25).should == 5
+      Integer.sqrt(10**400).should == 10**200
+    end
+
+    it "raises a Math::DomainError if the argument is negative" do
+      lambda { Integer.sqrt(-4) }.should raise_error(Math::DomainError)
+    end
+
+    it "accepts any argument that can be coerced to Integer" do
+      Integer.sqrt(10.0).should == 3
+    end
+
+    it "converts the argument with #to_int" do
+      Integer.sqrt(mock_int(10)).should == 3
+    end
+
+    it "raises a TypeError if the argument cannot be coerced to Integer" do
+      lambda { Integer.sqrt("test") }.should raise_error(TypeError)
+    end
+  end
+end

spec/ruby/core/integer/truncate_spec.rb

@@ -1,6 +1,21 @@
 require File.expand_path('../../../spec_helper', __FILE__)
 require File.expand_path('../shared/to_i', __FILE__)
+require File.expand_path('../shared/integer_rounding', __FILE__)
 
 describe "Integer#truncate" do
   it_behaves_like(:integer_to_i, :truncate)
+  it_behaves_like(:integer_rounding_positive_precision, :truncate)
+
+  ruby_version_is "2.4" do
+    context "precision argument specified as part of the truncate method is negative" do
+      it "returns an integer with at least precision.abs trailing zeros" do
+        1832.truncate(-1).should eql(1830)
+        1832.truncate(-2).should eql(1800)
+        1832.truncate(-3).should eql(1000)
+        -1832.truncate(-1).should eql(-1830)
+        -1832.truncate(-2).should eql(-1800)
+        -1832.truncate(-3).should eql(-1000)
+      end
+    end
+  end
 end

spec/ruby/core/io/advise_spec.rb

@@ -17,7 +17,7 @@ describe "IO#advise" do
     }.should raise_error(TypeError)
   end
 
-  it "raises a TypeError if offsert cannot be coerced to an Integer" do
+  it "raises a TypeError if offset cannot be coerced to an Integer" do
     lambda {
       @io.advise(:normal, "wat")
     }.should raise_error(TypeError)

spec/ruby/core/io/fixtures/classes.rb

@@ -20,6 +20,18 @@ module IOSpecs
       "Here is line six.\n" ]
   end
 
+  def self.lines_without_newline_characters
+    [ "Voici la ligne une.",
+      "Qui \303\250 la linea due.",
+      "",
+      "",
+      "Aqu\303\255 est\303\241 la l\303\255nea tres.",
+      "Hier ist Zeile vier.",
+      "",
+      "Est\303\241 aqui a linha cinco.",
+      "Here is line six." ]
+  end
+
   def self.lines_limit
     [ "Voici la l",
       "igne une.\n",

spec/ruby/core/io/gets_spec.rb

@@ -138,6 +138,14 @@ describe "IO#gets" do
       end
     end
   end
+
+  ruby_version_is "2.4" do
+    describe "when passed chomp" do
+      it "returns the first line without a trailing newline character" do
+        @io.gets(chomp: true).should == IOSpecs.lines_without_newline_characters[0]
+      end
+    end
+  end
 end
 
 describe "IO#gets" do
@@ -191,7 +199,7 @@ describe "IO#gets" do
     @io.gets(obj, 5).should == "one\n"
   end
 
-  it "reads to the default seperator when passed a single argument greater than the number of bytes to the separator" do
+  it "reads to the default separator when passed a single argument greater than the number of bytes to the separator" do
     @io.gets(6).should == "one\n"
   end
 

spec/ruby/core/io/readline_spec.rb

@@ -42,4 +42,12 @@ describe "IO#readline" do
       $_.should == line
     end
   end
+
+  ruby_version_is "2.4" do
+    describe "when passed chomp" do
+      it "returns the first line without a trailing newline character" do
+        @io.readline(chomp: true).should == IOSpecs.lines_without_newline_characters[0]
+      end
+    end
+  end
 end

spec/ruby/core/io/shared/each.rb

@@ -114,6 +114,15 @@ describe :io_each, shared: true do
       ScratchPad.recorded.should == IOSpecs.paragraphs
     end
   end
+
+  ruby_version_is "2.4" do
+    describe "when passed chomp" do
+      it "yields each line without trailing newline characters to the passed block" do
+        @io.send(@method, chomp: true) { |s| ScratchPad << s }
+        ScratchPad.recorded.should == IOSpecs.lines_without_newline_characters
+      end
+    end
+  end
 end
 
 describe :io_each_default_separator, shared: true do

spec/ruby/core/io/shared/readlines.rb

@@ -17,6 +17,13 @@ describe :io_readlines, shared: true do
     result = IO.send(@method, @name, "", &@object)
     (result ? result : ScratchPad.recorded).should == IOSpecs.lines_empty_separator
   end
+
+  ruby_version_is "2.4" do
+    it "yields a sequence of lines without trailing newline characters when chomp is passed" do
+      result = IO.send(@method, @name, chomp: true, &@object)
+      (result ? result : ScratchPad.recorded).should == IOSpecs.lines_without_newline_characters
+    end
+  end
 end
 
 describe :io_readlines_options_19, shared: true do

spec/ruby/core/kernel/equal_value_spec.rb

@@ -7,9 +7,9 @@ describe "Kernel#==" do
     o2 = mock('o2')
     (o1 == o1).should == true
     (o2 == o2).should == true
-    (o1 == o2).should== false
+    (o1 == o2).should == false
     (nil == nil).should == true
-    (o1 == nil).should== false
-    (nil == o2).should== false
+    (o1 == nil).should == false
+    (nil == o2).should == false
   end
 end

spec/ruby/core/main/fixtures/classes.rb

@@ -4,8 +4,11 @@ module MainSpecs
 
   module WrapIncludeModule
   end
+
+  DATA = {}
 end
 
+
 def main_public_method
 end
 public :main_public_method

spec/ruby/core/main/fixtures/string_refinement.rb

@@ -0,0 +1,7 @@
+module StringRefinement
+  refine(String) do
+    def foo
+      'foo'
+    end
+  end
+end

spec/ruby/core/main/fixtures/string_refinement_user.rb

@@ -0,0 +1,11 @@
+using StringRefinement
+
+module MainSpecs
+  DATA[:in_module] = 'hello'.foo
+
+  def self.call_foo(x)
+    x.foo
+  end
+end
+
+MainSpecs::DATA[:toplevel] = 'hello'.foo

spec/ruby/core/main/using_spec.rb

@@ -0,0 +1,134 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is "2.0.0" do
+  require File.expand_path('../fixtures/classes', __FILE__)
+  require File.expand_path('../fixtures/string_refinement', __FILE__)
+
+  describe "main.using" do
+    it "requires one Module argument" do
+      lambda do
+        eval('using', TOPLEVEL_BINDING)
+      end.should raise_error(ArgumentError)
+
+      lambda do
+        eval('using "foo"', TOPLEVEL_BINDING)
+      end.should raise_error(TypeError)
+    end
+
+    it "uses refinements from the given module only in the target file" do
+      load File.expand_path('../fixtures/string_refinement_user.rb', __FILE__)
+      MainSpecs::DATA[:in_module].should == 'foo'
+      MainSpecs::DATA[:toplevel].should == 'foo'
+      lambda do
+        'hello'.foo
+      end.should raise_error(NoMethodError)
+    end
+
+    it "uses refinements from the given module for method calls in the target file" do
+      load File.expand_path('../fixtures/string_refinement_user.rb', __FILE__)
+      lambda do
+        'hello'.foo
+      end.should raise_error(NoMethodError)
+      MainSpecs.call_foo('hello').should == 'foo'
+    end
+
+    it "uses refinements from the given module in the eval string" do
+      cls = MainSpecs::DATA[:cls] = Class.new {def foo; 'foo'; end}
+      MainSpecs::DATA[:mod] = Module.new do
+        refine(cls) do
+          def foo; 'bar'; end
+        end
+      end
+      eval(<<-EOS, TOPLEVEL_BINDING).should == 'bar'
+        using MainSpecs::DATA[:mod]
+        MainSpecs::DATA[:cls].new.foo
+      EOS
+    end
+
+    it "does not affect methods defined before it is called" do
+      cls = Class.new {def foo; 'foo'; end}
+      MainSpecs::DATA[:mod] = Module.new do
+        refine(cls) do
+          def foo; 'bar'; end
+        end
+      end
+      x = MainSpecs::DATA[:x] = Object.new
+      eval <<-EOS, TOPLEVEL_BINDING
+        x = MainSpecs::DATA[:x]
+        def x.before_using(obj)
+          obj.foo
+        end
+        using MainSpecs::DATA[:mod]
+        def x.after_using(obj)
+          obj.foo
+        end
+      EOS
+
+      obj = cls.new
+      x.before_using(obj).should == 'foo'
+      x.after_using(obj).should == 'bar'
+    end
+
+    it "propagates refinements added to existing modules after it is called" do
+      cls = Class.new {def foo; 'foo'; end}
+      mod = MainSpecs::DATA[:mod] = Module.new do
+        refine(cls) do
+          def foo; 'quux'; end
+        end
+      end
+      x = MainSpecs::DATA[:x] = Object.new
+      eval <<-EOS, TOPLEVEL_BINDING
+        using MainSpecs::DATA[:mod]
+        x = MainSpecs::DATA[:x]
+        def x.call_foo(obj)
+          obj.foo
+        end
+        def x.call_bar(obj)
+          obj.bar
+        end
+      EOS
+
+      obj = cls.new
+      x.call_foo(obj).should == 'quux'
+
+      mod.module_eval do
+        refine(cls) do
+          def bar; 'quux'; end
+        end
+      end
+
+      x.call_bar(obj).should == 'quux'
+    end
+
+    it "does not propagate refinements of new modules added after it is called" do
+      cls = Class.new {def foo; 'foo'; end}
+      cls2 = Class.new {def bar; 'bar'; end}
+      mod = MainSpecs::DATA[:mod] = Module.new do
+        refine(cls) do
+          def foo; 'quux'; end
+        end
+      end
+      x = MainSpecs::DATA[:x] = Object.new
+      eval <<-EOS, TOPLEVEL_BINDING
+        using MainSpecs::DATA[:mod]
+        x = MainSpecs::DATA[:x]
+        def x.call_foo(obj)
+          obj.foo
+        end
+        def x.call_bar(obj)
+          obj.bar
+        end
+      EOS
+
+      x.call_foo(cls.new).should == 'quux'
+
+      mod.module_eval do
+        refine(cls2) do
+          def bar; 'quux'; end
+        end
+      end
+
+      x.call_bar(cls2.new).should == 'bar'
+    end
+  end
+end

spec/ruby/core/module/fixtures/refine.rb

@@ -0,0 +1,13 @@
+module ModuleSpecs
+  class ClassWithFoo
+    def foo; "foo" end
+  end
+
+  module PrependedModule
+    def foo; "foo from prepended module"; end
+  end
+
+  module IncludedModule
+    def foo; "foo from included module"; end
+  end
+end

spec/ruby/core/module/fixtures/using.rb

@@ -0,0 +1,10 @@
+module ModuleSpecs
+  module EmptyRefinement
+  end
+
+  module RefinementForStringToS
+    refine String do
+      def to_s; "hello from refinement"; end
+    end
+  end
+end

spec/ruby/core/module/refine_spec.rb

@@ -0,0 +1,616 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/refine', __FILE__)
+
+describe "Module#refine" do
+  it "runs its block in an anonymous module" do
+    inner_self = nil
+    mod = Module.new do
+      refine String do
+        inner_self = self
+      end
+    end
+
+    mod.should_not == inner_self
+    inner_self.should be_kind_of(Module)
+    inner_self.name.should == nil
+  end
+
+  it "uses the same anonymous module for future refines of the same class" do
+    selves = []
+    mod = Module.new do
+      refine String do
+        selves << self
+      end
+    end
+
+    mod.module_eval do
+      refine String do
+        selves << self
+      end
+    end
+
+    selves[0].should == selves[1]
+  end
+
+  it "adds methods defined in its block to the anonymous module's public instance methods" do
+    inner_self = nil
+    mod = Module.new do
+      refine String do
+        def blah
+          "blah"
+        end
+        inner_self = self
+      end
+    end
+
+    inner_self.public_instance_methods.should include(:blah)
+  end
+
+  it "returns created anonymous module" do
+    inner_self = nil
+    result = nil
+    mod = Module.new do
+      result = refine String do
+        inner_self = self
+      end
+    end
+
+    result.should == inner_self
+  end
+
+  it "raises ArgumentError if not passed an argument" do
+    lambda do
+      Module.new do
+        refine {}
+      end
+    end.should raise_error(ArgumentError)
+  end
+
+  it "raises TypeError if not passed a class" do
+    lambda do
+      Module.new do
+        refine("foo") {}
+      end
+    end.should raise_error(TypeError)
+  end
+
+  ruby_version_is "" ... "2.4" do
+    it "raises TypeError if passed a module" do
+      lambda do
+        Module.new do
+          refine(Enumerable) {}
+        end
+      end.should raise_error(TypeError)
+    end
+  end
+
+  ruby_version_is "2.4" do
+    it "accepts a module as argument" do
+      inner_self = nil
+      Module.new do
+        refine(Enumerable) do
+          def blah
+          end
+          inner_self = self
+        end
+      end
+
+      inner_self.public_instance_methods.should include(:blah)
+    end
+  end
+
+  it "raises ArgumentError if not given a block" do
+    lambda do
+      Module.new do
+        refine String
+      end
+    end.should raise_error(ArgumentError)
+  end
+
+  it "applies refinements to calls in the refine block" do
+    result = nil
+    Module.new do
+      refine(String) do
+        def foo; "foo"; end
+        result = "hello".foo
+      end
+    end
+    result.should == "foo"
+  end
+
+  it "doesn't apply refinements outside the refine block" do
+    Module.new do
+      refine(String) {def foo; "foo"; end}
+      -> () {
+        "hello".foo
+      }.should raise_error(NoMethodError)
+    end
+  end
+
+  it "does not apply refinements to external scopes not using the module" do
+    Module.new do
+      refine(String) {def foo; 'foo'; end}
+    end
+
+    lambda {"hello".foo}.should raise_error(NoMethodError)
+  end
+
+  # When defining multiple refinements in the same module,
+  # inside a refine block all refinements from the same
+  # module are active when a refined method is called
+  it "makes available all refinements from the same module" do
+    refinement = Module.new do
+      refine Integer do
+        def to_json_format
+          to_s
+        end
+      end
+
+      refine Array do
+        def to_json_format
+          "[" + map { |i| i.to_json_format }.join(", ") + "]"
+        end
+      end
+
+      refine Hash do
+        def to_json_format
+          "{" + map { |k, v| k.to_s.dump + ": " + v.to_json_format }.join(", ") + "}"
+        end
+      end
+    end
+
+    result = nil
+
+    Module.new do
+      using refinement
+
+      result = [{1 => 2}, {3 => 4}].to_json_format
+    end
+
+    result.should == '[{"1": 2}, {"3": 4}]'
+  end
+
+  it "does not make available methods from another refinement module" do
+    refinery_integer = Module.new do
+      refine Integer do
+        def to_json_format
+          to_s
+        end
+      end
+    end
+
+    refinery_array = Module.new do
+      refine Array do
+        def to_json_format
+          "[" + map { |i| i.to_json_format }.join(",") + "]"
+        end
+      end
+    end
+
+    result = nil
+
+    -> () {
+      Module.new do
+        using refinery_integer
+        using refinery_array
+
+        [1, 2].to_json_format
+      end
+    }.should raise_error(NoMethodError)
+  end
+
+  # method lookup:
+  #   * The prepended modules from the refinement for C
+  #   * The refinement for C
+  #   * The included modules from the refinement for C
+  #   * The prepended modules of C
+  #   * C
+  #   * The included modules of C
+  describe "method lookup" do
+    it "looks in the object singleton class first" do
+      refinement = Module.new do
+        refine ModuleSpecs::ClassWithFoo  do
+          def foo; "foo from refinement"; end
+        end
+      end
+
+      result = nil
+      Module.new do
+        using refinement
+
+        obj = ModuleSpecs::ClassWithFoo.new
+        class << obj
+          def foo; "foo from singleton class"; end
+        end
+        result = obj.foo
+      end
+
+      result.should == "foo from singleton class"
+    end
+
+    it "looks in prepended modules from the refinement first" do
+      refinement = Module.new do
+        refine ModuleSpecs::ClassWithFoo  do
+          include ModuleSpecs::IncludedModule
+          prepend ModuleSpecs::PrependedModule
+
+          def foo; "foo from refinement"; end
+        end
+      end
+
+      result = nil
+      Module.new do
+        using refinement
+        result = ModuleSpecs::ClassWithFoo.new.foo
+      end
+
+      result.should == "foo from prepended module"
+    end
+
+    it "looks in refinement then" do
+      refinement = Module.new do
+        refine(ModuleSpecs::ClassWithFoo) do
+          include ModuleSpecs::IncludedModule
+
+          def foo; "foo from refinement"; end
+        end
+      end
+
+      result = nil
+      Module.new do
+        using refinement
+        result = ModuleSpecs::ClassWithFoo.new.foo
+      end
+
+      result.should == "foo from refinement"
+    end
+
+    it "looks in included modules from the refinement then" do
+      refinement = Module.new do
+        refine ModuleSpecs::ClassWithFoo  do
+          include ModuleSpecs::IncludedModule
+        end
+      end
+
+      result = nil
+      Module.new do
+        using refinement
+        result = ModuleSpecs::ClassWithFoo.new.foo
+      end
+
+      result.should == "foo from included module"
+    end
+
+    it "looks in the class then" do
+      refinement = Module.new do
+        refine(ModuleSpecs::ClassWithFoo) { }
+      end
+
+      result = nil
+      Module.new do
+        using refinement
+        result = ModuleSpecs::ClassWithFoo.new.foo
+      end
+
+      result.should == "foo"
+    end
+  end
+
+
+  # methods in a subclass have priority over refinements in a superclass
+  it "does not override methods in subclasses" do
+    subclass = Class.new(ModuleSpecs::ClassWithFoo) do
+      def foo; "foo from subclass"; end
+    end
+
+    refinement = Module.new do
+      refine ModuleSpecs::ClassWithFoo do
+        def foo; "foo from refinement"; end
+      end
+    end
+
+    result = nil
+    Module.new do
+      using refinement
+      result = subclass.new.foo
+    end
+
+    result.should == "foo from subclass"
+  end
+
+  context "for methods accesses indirectly" do
+    ruby_version_is "" ... "2.4" do
+      it "is not honored by Kernel#send" do
+        refinement = Module.new do
+          refine ModuleSpecs::ClassWithFoo do
+            def foo; "foo from refinement"; end
+          end
+        end
+
+        result = nil
+        Module.new do
+          using refinement
+          result = ModuleSpecs::ClassWithFoo.new.send :foo
+        end
+
+        result.should == "foo"
+      end
+
+      it "is not honored by BasicObject#__send__" do
+        refinement = Module.new do
+          refine ModuleSpecs::ClassWithFoo do
+            def foo; "foo from refinement"; end
+          end
+        end
+
+        result = nil
+        Module.new do
+          using refinement
+          result = ModuleSpecs::ClassWithFoo.new.__send__ :foo
+        end
+
+        result.should == "foo"
+      end
+
+      it "is not honored by Symbol#to_proc" do
+        refinement = Module.new do
+          refine Integer do
+            def to_s
+              "(#{super})"
+            end
+          end
+        end
+
+        result = nil
+        Module.new do
+          using refinement
+          result = [1, 2, 3].map(&:to_s)
+        end
+
+        result.should == ["1", "2", "3"]
+      end
+    end
+
+    ruby_version_is "2.4" do
+      it "is honored by Kernel#send" do
+        refinement = Module.new do
+          refine ModuleSpecs::ClassWithFoo do
+            def foo; "foo from refinement"; end
+          end
+        end
+
+        result = nil
+        Module.new do
+          using refinement
+          result = ModuleSpecs::ClassWithFoo.new.send :foo
+        end
+
+        result.should == "foo from refinement"
+      end
+
+      it "is honored by BasicObject#__send__" do
+        refinement = Module.new do
+          refine ModuleSpecs::ClassWithFoo do
+            def foo; "foo from refinement"; end
+          end
+        end
+
+        result = nil
+        Module.new do
+          using refinement
+          result = ModuleSpecs::ClassWithFoo.new.__send__ :foo
+        end
+
+        result.should == "foo from refinement"
+      end
+
+      it "is honored by Symbol#to_proc" do
+        refinement = Module.new do
+          refine Integer do
+            def to_s
+              "(#{super})"
+            end
+          end
+        end
+
+        result = nil
+        Module.new do
+          using refinement
+          result = [1, 2, 3].map(&:to_s)
+        end
+
+        result.should == ["(1)", "(2)", "(3)"]
+      end
+    end
+
+    it "is honored by Kernel#binding" do
+      refinement = Module.new do
+        refine String do
+          def to_s
+            "hello from refinement"
+          end
+        end
+      end
+
+      klass = Class.new do
+        using refinement
+
+        def foo
+          "foo".to_s
+        end
+
+        def get_binding
+          binding
+        end
+      end
+
+      result = Kernel.eval("self.foo()", klass.new.get_binding)
+      result.should == "hello from refinement"
+    end
+
+    it "is not honored by Kernel#method" do
+      klass = Class.new
+      refinement = Module.new do
+        refine klass do
+          def foo; end
+        end
+      end
+
+      -> {
+        Module.new do
+          using refinement
+          klass.new.method(:foo)
+        end
+      }.should raise_error(NameError, /undefined method `foo'/)
+    end
+
+    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)
+      end
+
+      result.should == false
+    end
+  end
+
+  context "when super is called in a refinement" do
+    it "looks in the included to refinery module" do
+      refinement = Module.new do
+        refine ModuleSpecs::ClassWithFoo  do
+          include ModuleSpecs::IncludedModule
+
+          def foo
+            super
+          end
+        end
+      end
+
+      result = nil
+      Module.new do
+        using refinement
+        result = ModuleSpecs::ClassWithFoo.new.foo
+      end
+
+      result.should == "foo from included module"
+    end
+
+    it "looks in the refined class" do
+      refinement = Module.new do
+        refine ModuleSpecs::ClassWithFoo  do
+          def foo
+            super
+          end
+        end
+      end
+
+      result = nil
+      Module.new do
+        using refinement
+        result = ModuleSpecs::ClassWithFoo.new.foo
+      end
+
+      result.should == "foo"
+    end
+
+    # super in a method of a refinement invokes the method in the refined
+    # class even if there is another refinement which has been activated
+    # in the same context.
+    it "looks in the refined class even if there is another active refinement" do
+      refinement = Module.new do
+        refine ModuleSpecs::ClassWithFoo  do
+          def foo
+            "foo from refinement"
+          end
+        end
+      end
+
+      refinement_with_super = Module.new do
+        refine ModuleSpecs::ClassWithFoo  do
+          def foo
+            super
+          end
+        end
+      end
+
+      result = nil
+      Module.new do
+        using refinement
+        using refinement_with_super
+        result = ModuleSpecs::ClassWithFoo.new.foo
+      end
+
+      result.should == "foo"
+    end
+  end
+
+  # Refinements are inherited by module inclusion.
+  # That is, using activates all refinements in the ancestors of the specified module.
+  # Refinements in a descendant have priority over refinements in an ancestor.
+  context "module inclusion" do
+    it "activates all refinements from all ancestors" do
+      refinement_included = Module.new do
+        refine Integer do
+          def to_json_format
+            to_s
+          end
+        end
+      end
+
+      refinement = Module.new do
+        include refinement_included
+
+        refine Array do
+          def to_json_format
+            "[" + map { |i| i.to_s }.join(", ") + "]"
+          end
+        end
+      end
+
+      result = nil
+      Module.new do
+        using refinement
+        result = [5.to_json_format, [1, 2, 3].to_json_format]
+      end
+
+      result.should == ["5", "[1, 2, 3]"]
+    end
+
+    it "overrides methods of ancestors by methods in descendants" do
+      refinement_included = Module.new do
+        refine Integer do
+          def to_json_format
+            to_s
+          end
+        end
+      end
+
+      refinement = Module.new do
+        include refinement_included
+
+        refine Integer do
+          def to_json_format
+            "hello from refinement"
+          end
+        end
+      end
+
+      result = nil
+      Module.new do
+        using refinement
+        result = 5.to_json_format
+      end
+
+      result.should == "hello from refinement"
+    end
+  end
+end
+

spec/ruby/core/module/using_spec.rb

@@ -0,0 +1,276 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/using', __FILE__)
+
+describe "Module#using" do
+  it "imports class refinements from module into the current class/module" do
+    refinement = Module.new do
+      refine Integer do
+        def foo; "foo"; end
+      end
+    end
+
+    result = nil
+    Module.new do
+      using refinement
+      result = 1.foo
+    end
+
+    result.should == "foo"
+  end
+
+  it "accepts module as argument" do
+    refinement = Module.new do
+      refine Integer do
+        def foo; "foo"; end
+      end
+    end
+
+    -> () {
+      Module.new do
+        using refinement
+      end
+    }.should_not raise_error
+  end
+
+  it "accepts module without refinements" do
+    mod = Module.new
+
+    -> () {
+      Module.new do
+        using mod
+      end
+    }.should_not raise_error
+  end
+
+  it "does not accept class" do
+    klass = Class.new
+
+    -> () {
+      Module.new do
+        using klass
+      end
+    }.should raise_error(TypeError)
+  end
+
+  it "raises TypeError if passed something other than module" do
+    -> () {
+      Module.new do
+        using "foo"
+      end
+    }.should raise_error(TypeError)
+  end
+
+  it "returns self" do
+    refinement = Module.new
+
+    result = nil
+    mod = Module.new do
+      result = using refinement
+    end
+
+    result.should equal(mod)
+  end
+
+  it "works in classes too" do
+    refinement = Module.new do
+      refine Integer do
+        def foo; "foo"; end
+      end
+    end
+
+    result = nil
+    Class.new do
+      using refinement
+      result = 1.foo
+    end
+
+    result.should == "foo"
+  end
+
+  it "raises error in method scope" do
+    mod = Module.new do
+      def self.foo
+        using ModuleSpecs::EmptyRefinement
+      end
+    end
+
+    -> () {
+      mod.foo
+    }.should raise_error(RuntimeError, /Module#using is not permitted in methods/)
+  end
+
+  it "activates refinement even for existed objects" do
+    result = nil
+
+    Module.new do
+      klass = Class.new do
+        def foo; "foo"; end
+      end
+
+      refinement = Module.new do
+        refine klass do
+          def foo; "foo from refinement"; end
+        end
+      end
+
+      obj = klass.new
+      using refinement
+      result = obj.foo
+    end
+
+    result.should == "foo from refinement"
+  end
+
+  it "activates updates when refinement reopens later" do
+    result = nil
+
+    Module.new do
+      klass = Class.new do
+        def foo; "foo"; end
+      end
+
+      refinement = Module.new do
+        refine klass do
+          def foo; "foo from refinement"; end
+        end
+      end
+
+      using refinement
+
+      refinement.class_eval do
+        refine klass do
+          def foo; "foo from reopened refinement"; end
+        end
+      end
+
+      obj = klass.new
+      result = obj.foo
+    end
+
+    result.should == "foo from reopened refinement"
+  end
+
+  describe "scope of refinement" do
+    it "is active until the end of current class/module" do
+      ScratchPad.record []
+
+      Module.new do
+        Class.new do
+          using ModuleSpecs::RefinementForStringToS
+          ScratchPad << "1".to_s
+        end
+
+        ScratchPad << "1".to_s
+      end
+
+      ScratchPad.recorded.should == ["hello from refinement", "1"]
+    end
+
+    # Refinements are lexical in scope.
+    # Refinements are only active within a scope after the call to using.
+    # Any code before the using statement will not have the refinement activated.
+    it "is not active before the `using` call" do
+      ScratchPad.record []
+
+      Module.new do
+        Class.new do
+          ScratchPad << "1".to_s
+          using ModuleSpecs::RefinementForStringToS
+          ScratchPad << "1".to_s
+        end
+      end
+
+      ScratchPad.recorded.should == ["1", "hello from refinement"]
+    end
+
+    # If you call a method that is defined outside the current scope
+    # the refinement will be deactivated
+    it "is not active for code defined outside the current scope" do
+      result = nil
+
+      Module.new do
+        klass = Class.new do
+          def foo; "foo"; end
+        end
+
+        refinement = Module.new do
+          refine klass do
+            def foo; "foo from refinement"; end
+          end
+        end
+
+        def self.call_foo(c)
+          c.foo
+        end
+
+        using refinement
+
+        result = call_foo(klass.new)
+      end
+
+      result.should == "foo"
+    end
+
+    # If a method is defined in a scope where a refinement is active
+    # the refinement will be active when the method is called.
+    it "is active for method defined in a scope wherever it's called" do
+      klass = Class.new do
+        def foo; "foo"; end
+      end
+
+      mod = Module.new do
+        refinement = Module.new do
+          refine klass do
+            def foo; "foo from refinement"; end
+          end
+        end
+
+        using refinement
+
+        def self.call_foo(c)
+          c.foo
+        end
+      end
+
+      c = klass.new
+      mod.call_foo(c).should == "foo from refinement"
+    end
+
+    it "is not active if `using` call is not evaluated" do
+      result = nil
+
+      Module.new do
+        if false
+          using ModuleSpecs::RefinementForStringToS
+        end
+        result = "1".to_s
+      end
+
+      result.should == "1"
+    end
+
+    # The refinements in module are not activated automatically
+    # if the class is reopened later
+    it "is not active when class/module reopens" do
+      refinement = Module.new do
+        refine String do
+          def to_s
+            "hello from refinement"
+          end
+        end
+      end
+
+      result = []
+      klass = Class.new do
+        using refinement
+        result << "1".to_s
+      end
+
+      klass.class_eval do
+        result << "1".to_s
+      end
+
+      result.should == ["hello from refinement", "1"]
+    end
+  end
+end

spec/ruby/core/mutex/lock_spec.rb

@@ -33,14 +33,9 @@ describe "Mutex#lock" do
   # related to this ML thread.
   it "raises a ThreadError when used recursively" do
     m = Mutex.new
-
-    th = Thread.new do
+    m.lock
+    -> {
       m.lock
-      m.lock
-    end
-
-    lambda do
-      th.join
-    end.should raise_error(ThreadError)
+    }.should raise_error(ThreadError)
   end
 end

spec/ruby/core/nil/dup_spec.rb

@@ -0,0 +1,9 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is '2.4' do
+  describe "NilClass#dup" do
+    it "returns self" do
+      nil.dup.should equal(nil)
+    end
+  end
+end

spec/ruby/core/numeric/coerce_spec.rb

@@ -17,7 +17,7 @@ describe "Numeric#coerce" do
   # I (emp) think that this behavior is actually a bug in MRI. It's here as documentation
   # of the behavior until we find out if it's a bug.
   quarantine! do
-    it "considers the presense of a metaclass when checking the class of the objects" do
+    it "considers the presence of a metaclass when checking the class of the objects" do
       a = NumericSpecs::Subclass.new
       b = NumericSpecs::Subclass.new
 

spec/ruby/core/numeric/finite_spec.rb

@@ -0,0 +1,10 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is "2.4" do
+  describe "Numeric#finite?" do
+    it "returns true by default" do
+      o = mock_numeric("finite")
+      o.finite?.should be_true
+    end
+  end
+end

spec/ruby/core/numeric/infinite_spec.rb

@@ -0,0 +1,10 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is "2.4" do
+  describe "Numeric#infinite?" do
+    it "returns nil by default" do
+      o = mock_numeric("infinite")
+      o.infinite?.should == nil
+    end
+  end
+end

spec/ruby/core/process/wait2_spec.rb

@@ -5,8 +5,11 @@ describe "Process.wait2" do
     # HACK: this kludge is temporarily necessary because some
     # misbehaving spec somewhere else does not clear processes
     begin
+      Process.wait(-1, Process::WNOHANG)
+      $stderr.puts "Leaked process before wait2 specs! Waiting for it"
       leaked = Process.waitall
-      puts "leaked before wait2 specs: #{leaked}" unless leaked.empty?
+      $stderr.puts "leaked before wait2 specs: #{leaked}"
+    rescue Errno::ECHILD # No child processes
     rescue NotImplementedError
     end
   end

spec/ruby/core/random/bytes_spec.rb

@@ -19,14 +19,14 @@ describe "Random#bytes" do
   end
 
   # Should double check this is official spec
-  it "returns the same numeric output for a given seed accross all implementations and platforms" do
+  it "returns the same numeric output for a given seed across all implementations and platforms" do
     rnd = Random.new(33)
     rnd.bytes(2).should == "\x14\\"
     rnd.bytes(1000) # skip some
     rnd.bytes(2).should == "\xA1p"
   end
 
-  it "returns the same numeric output for a given huge seed accross all implementations and platforms" do
+  it "returns the same numeric output for a given huge seed across all implementations and platforms" do
     rnd = Random.new(bignum_value ** 4)
     rnd.bytes(2).should == "_\x91"
     rnd.bytes(1000) # skip some

spec/ruby/core/string/capitalize_spec.rb

@@ -44,6 +44,14 @@ describe "String#capitalize!" do
     a.should == "Hello"
   end
 
+  ruby_version_is '2.4' do
+    it "capitalizes self in place for all of Unicode" do
+      a = "äöü"
+      a.capitalize!.should equal(a)
+      a.should == "Äöü"
+    end
+  end
+
   it "returns nil when no changes are made" do
     a = "Hello"
     a.capitalize!.should == nil

spec/ruby/core/string/casecmp_spec.rb

@@ -1,4 +1,4 @@
-# -*- encoding: ascii-8bit -*-
+# -*- encoding: utf-8 -*-
 require File.expand_path('../../../spec_helper', __FILE__)
 require File.expand_path('../fixtures/classes.rb', __FILE__)
 
@@ -40,10 +40,10 @@ describe "String#casecmp independent of case" do
   describe "in UTF-8 mode" do
     describe "for non-ASCII characters" do
       before :each do
-        @upper_a_tilde  = "\xc3\x83"
-        @lower_a_tilde  = "\xc3\xa3"
-        @upper_a_umlaut = "\xc3\x84"
-        @lower_a_umlaut = "\xc3\xa4"
+        @upper_a_tilde  = "Ã"
+        @lower_a_tilde  = "ã"
+        @upper_a_umlaut = "Ä"
+        @lower_a_umlaut = "ä"
       end
 
       it "returns -1 when numerically less than other" do
@@ -118,3 +118,67 @@ describe "String#casecmp independent of case" do
     end
   end
 end
+
+ruby_version_is "2.4" do
+  describe 'String#casecmp? independent of case' do
+    it 'returns true when equal to other' do
+      'abc'.casecmp?('abc').should == true
+      'abc'.casecmp?('ABC').should == true
+    end
+
+    it 'returns false when not equal to other' do
+      'abc'.casecmp?('DEF').should == false
+      'abc'.casecmp?('def').should == false
+    end
+
+    it "tries to convert other to string using to_str" do
+      other = mock('x')
+      other.should_receive(:to_str).and_return("abc")
+
+      "abc".casecmp?(other).should == true
+    end
+
+    describe 'for UNICODE characters' do
+      it 'returns true when downcase(:fold) on unicode' do
+        'äöü'.casecmp?('ÄÖÜ').should == true
+      end
+    end
+
+    describe "when comparing a subclass instance" do
+      it 'returns true when equal to other' do
+        a = StringSpecs::MyString.new "a"
+        'a'.casecmp?(a).should == true
+        'A'.casecmp?(a).should == true
+      end
+
+      it 'returns false when not equal to other' do
+        b = StringSpecs::MyString.new "a"
+        'b'.casecmp?(b).should == false
+        'B'.casecmp?(b).should == false
+      end
+    end
+
+    describe "in UTF-8 mode" do
+      describe "for non-ASCII characters" do
+        before :each do
+          @upper_a_tilde  = "Ã"
+          @lower_a_tilde  = "ã"
+          @upper_a_umlaut = "Ä"
+          @lower_a_umlaut = "ä"
+        end
+
+        it "returns true when they are the same with normalized case" do
+          @upper_a_tilde.casecmp?(@lower_a_tilde).should == true
+        end
+
+        it "returns false when they are unrelated" do
+          @upper_a_tilde.casecmp?(@upper_a_umlaut).should == false
+        end
+
+        it "returns true when they have the same bytes" do
+          @upper_a_tilde.casecmp?(@upper_a_tilde).should == true
+        end
+      end
+    end
+  end
+end

spec/ruby/core/string/downcase_spec.rb

@@ -46,6 +46,14 @@ describe "String#downcase!" do
     a.should == "hello"
   end
 
+  ruby_version_is '2.4' do
+    it "modifies self in place for all of Unicode" do
+      a = "ÄÖÜ"
+      a.downcase!.should equal(a)
+      a.should == "äöü"
+    end
+  end
+
   it "returns nil if no modifications were made" do
     a = "hello"
     a.downcase!.should == nil

spec/ruby/core/string/lines_spec.rb

@@ -10,4 +10,13 @@ describe "String#lines" do
     ary = "hello world".send(@method, ' ')
     ary.should == ["hello ", "world"]
   end
+
+  ruby_version_is '2.4' do
+    context "when `chomp` keyword argument is passed" do
+      it "removes new line characters" do
+        "hello \nworld\n".lines(chomp: true).should == ["hello ", "world"]
+        "hello \r\nworld\r\n".lines(chomp: true).should == ["hello ", "world"]
+      end
+    end
+  end
 end

spec/ruby/core/string/new_spec.rb

@@ -15,6 +15,13 @@ describe "String.new" do
     end
   end
 
+  ruby_version_is "2.4" do
+    it "accepts a capacity argument" do
+      String.new("", capacity: 100_000).should == ""
+      String.new("abc", capacity: 100_000).should == "abc"
+    end
+  end
+
   it "returns a fully-formed String" do
     str = String.new
     str.size.should == 0

spec/ruby/core/string/shared/chars.rb

@@ -42,10 +42,8 @@ describe :string_chars, shared: true do
     it "returns a different character if the String is transcoded" do
       s = "\u{20AC}".force_encoding('UTF-8')
       s.encode('UTF-8').send(@method).to_a.should == ["\u{20AC}".force_encoding('UTF-8')]
-      s.encode('iso-8859-15').send(@method).to_a.should == [
-        [0xA4].pack('C').force_encoding('iso-8859-15')]
-      s.encode('iso-8859-15').encode('UTF-8').send(@method).to_a.should == [
-        "\u{20AC}".force_encoding('UTF-8')]
+      s.encode('iso-8859-15').send(@method).to_a.should == [[0xA4].pack('C').force_encoding('iso-8859-15')]
+      s.encode('iso-8859-15').encode('UTF-8').send(@method).to_a.should == ["\u{20AC}".force_encoding('UTF-8')]
     end
 
     it "uses the String's encoding to determine what characters it contains" do

spec/ruby/core/string/shared/codepoints.rb

@@ -48,7 +48,7 @@ describe :string_codepoints, shared: true do
     s.should == s2
   end
 
-  it "is synonomous with #bytes for Strings which are single-byte optimisable" do
+  it "is synonymous with #bytes for Strings which are single-byte optimisable" do
     s = "(){}".encode('ascii')
     s.ascii_only?.should be_true
     s.send(@method).to_a.should == s.bytes.to_a

spec/ruby/core/string/shared/each_line.rb

@@ -133,4 +133,18 @@ end
   it "raises a TypeError when the separator is a symbol" do
     lambda { "hello world".send(@method, :o).to_a }.should raise_error(TypeError)
   end
+
+  ruby_version_is '2.4' do
+    context "when `chomp` keyword argument is passed" do
+      it "removes new line characters" do
+        a = []
+        "hello \nworld\n".send(@method, chomp: true) { |s| a << s }
+        a.should == ["hello ", "world"]
+
+        a = []
+        "hello \r\nworld\r\n".send(@method, chomp: true) { |s| a << s }
+        a.should == ["hello ", "world"]
+      end
+    end
+  end
 end

spec/ruby/core/string/shared/to_sym.rb

@@ -1,24 +1,63 @@
 describe :string_to_sym, shared: true do
   it "returns the symbol corresponding to self" do
-    "Koala".send(@method).should == :Koala
-    'cat'.send(@method).should == :cat
-    '@cat'.send(@method).should == :@cat
-    'cat and dog'.send(@method).should == :"cat and dog"
-    "abc=".send(@method).should == :abc=
+    "Koala".send(@method).should equal :Koala
+    'cat'.send(@method).should equal :cat
+    '@cat'.send(@method).should equal :@cat
+    'cat and dog'.send(@method).should equal :"cat and dog"
+    "abc=".send(@method).should equal :abc=
   end
 
   it "does not special case +(binary) and -(binary)" do
-    "+(binary)".send(@method).should == :"+(binary)"
-    "-(binary)".send(@method).should == :"-(binary)"
+    "+(binary)".send(@method).should equal :"+(binary)"
+    "-(binary)".send(@method).should equal :"-(binary)"
   end
 
   it "does not special case certain operators" do
-    [ ["!@", :"!@"],
-      ["~@", :"~@"],
-      ["!(unary)", :"!(unary)"],
-      ["~(unary)", :"~(unary)"],
-      ["+(unary)", :"+(unary)"],
-      ["-(unary)", :"-(unary)"]
-    ].should be_computed_by(@method)
+    "!@".send(@method).should equal :"!@"
+    "~@".send(@method).should equal :"~@"
+    "!(unary)".send(@method).should equal :"!(unary)"
+    "~(unary)".send(@method).should equal :"~(unary)"
+    "+(unary)".send(@method).should equal :"+(unary)"
+    "-(unary)".send(@method).should equal :"-(unary)"
+  end
+
+  it "returns a US-ASCII Symbol for a UTF-8 String containing only US-ASCII characters" do
+    sym = "foobar".send(@method)
+    sym.encoding.should == Encoding::US_ASCII
+    sym.should equal :"foobar"
+  end
+
+  it "returns a US-ASCII Symbol for a binary String containing only US-ASCII characters" do
+    sym = "foobar".b.send(@method)
+    sym.encoding.should == Encoding::US_ASCII
+    sym.should equal :"foobar"
+  end
+
+  it "returns a UTF-8 Symbol for a UTF-8 String containing non US-ASCII characters" do
+    sym = "il était une fois".send(@method)
+    sym.encoding.should == Encoding::UTF_8
+    sym.should equal :"il était une #{'fois'}"
+  end
+
+  it "returns a UTF-16LE Symbol for a UTF-16LE String containing non US-ASCII characters" do
+    utf16_str = "UtéF16".encode(Encoding::UTF_16LE)
+    sym = utf16_str.send(@method)
+    sym.encoding.should == Encoding::UTF_16LE
+    sym.to_s.should == utf16_str
+  end
+
+  it "returns a binary Symbol for a binary String containing non US-ASCII characters" do
+    binary_string = "binarí".b
+    sym = binary_string.send(@method)
+    sym.encoding.should == Encoding::BINARY
+    sym.to_s.should == binary_string
+  end
+
+  it "raises an EncodingError for UTF-8 String containing invalid bytes" do
+    invalid_utf8 = "\xC3"
+    invalid_utf8.valid_encoding?.should == false
+    -> {
+      invalid_utf8.send(@method)
+    }.should raise_error(EncodingError, /invalid/)
   end
 end

spec/ruby/core/string/swapcase_spec.rb

@@ -41,6 +41,14 @@ describe "String#swapcase!" do
     a.should == "CyBeR_pUnK11"
   end
 
+  ruby_version_is '2.4' do
+    it "modifies self in place for all of Unicode" do
+      a = "äÖü"
+      a.swapcase!.should equal(a)
+      a.should == "ÄöÜ"
+    end
+  end
+
   it "returns nil if no modifications were made" do
     a = "+++---111222???"
     a.swapcase!.should == nil

spec/ruby/core/string/unpack1_spec.rb

@@ -0,0 +1,12 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is "2.4" do
+  describe "String#unpack1" do
+    it "returns the first value of #unpack" do
+      "ABCD".unpack1('x3C').should == "ABCD".unpack('x3C')[0]
+      "\u{3042 3044 3046}".unpack1("U*").should == 0x3042
+      "aG9nZWZ1Z2E=".unpack1("m").should == "hogefuga"
+      "A".unpack1("B*").should == "01000001"
+    end
+  end
+end

spec/ruby/core/string/upcase_spec.rb

@@ -46,6 +46,15 @@ describe "String#upcase!" do
     a.should == "HELLO"
   end
 
+
+  ruby_version_is '2.4' do
+    it "modifies self in place for all of Unicode" do
+      a = "äöü"
+      a.upcase!.should equal(a)
+      a.should == "ÄÖÜ"
+    end
+  end
+
   it "returns nil if no modifications were made" do
     a = "HELLO"
     a.upcase!.should == nil

spec/ruby/core/struct/initialize_spec.rb

@@ -37,7 +37,7 @@ describe "Struct#initialize" do
     car.make.should == nil # still nil despite override in Honda#initialize b/c of super order
   end
 
-  it "can be overriden" do
+  it "can be overridden" do
     StructClasses::SubclassX.new(:y).new.key.should == :value
   end
 end

spec/ruby/core/symbol/capitalize_spec.rb

@@ -21,6 +21,13 @@ describe "Symbol#capitalize" do
     end
   end
 
+  ruby_version_is '2.4' do
+    it "capitalizes the first character if it is Unicode" do
+      :"äöü".capitalize.should == :"Äöü"
+      :"aou".capitalize.should == :"Aou"
+    end
+  end
+
   it "converts subsequent uppercase ASCII characters to their lowercase equivalents" do
     :lOWER.capitalize.should == :Lower
   end

spec/ruby/core/symbol/casecmp_spec.rb

@@ -1,4 +1,4 @@
-# -*- encoding: binary -*-
+# -*- encoding: utf-8 -*-
 require File.expand_path('../../../spec_helper', __FILE__)
 
 describe "Symbol#casecmp with Symbol" do
@@ -11,10 +11,10 @@ describe "Symbol#casecmp with Symbol" do
 
   it "doesn't consider non-ascii characters equal that aren't" do
     # -- Latin-1 --
-    upper_a_tilde  = :"\xC3"
-    upper_a_umlaut = :"\xC4"
-    lower_a_tilde  = :"\xE3"
-    lower_a_umlaut = :"\xE4"
+    upper_a_tilde  = "\xC3".b.to_sym
+    upper_a_umlaut = "\xC4".b.to_sym
+    lower_a_tilde  = "\xE3".b.to_sym
+    lower_a_umlaut = "\xE4".b.to_sym
 
     lower_a_tilde.casecmp(lower_a_umlaut).should_not == 0
     lower_a_umlaut.casecmp(lower_a_tilde).should_not == 0
@@ -22,10 +22,10 @@ describe "Symbol#casecmp with Symbol" do
     upper_a_umlaut.casecmp(upper_a_tilde).should_not == 0
 
     # -- UTF-8 --
-    upper_a_tilde  = :"\xC3\x83"
-    upper_a_umlaut = :"\xC3\x84"
-    lower_a_tilde  = :"\xC3\xA3"
-    lower_a_umlaut = :"\xC3\xA4"
+    upper_a_tilde  = :"Ã"
+    lower_a_tilde  = :"ã"
+    upper_a_umlaut = :"Ä"
+    lower_a_umlaut = :"ä"
 
     lower_a_tilde.casecmp(lower_a_umlaut).should_not == 0
     lower_a_umlaut.casecmp(lower_a_tilde).should_not == 0
@@ -35,10 +35,10 @@ describe "Symbol#casecmp with Symbol" do
 
   it "doesn't do case mapping for non-ascii characters" do
     # -- Latin-1 --
-    upper_a_tilde  = :"\xC3"
-    upper_a_umlaut = :"\xC4"
-    lower_a_tilde  = :"\xE3"
-    lower_a_umlaut = :"\xE4"
+    upper_a_tilde  = "\xC3".b.to_sym
+    upper_a_umlaut = "\xC4".b.to_sym
+    lower_a_tilde  = "\xE3".b.to_sym
+    lower_a_umlaut = "\xE4".b.to_sym
 
     upper_a_tilde.casecmp(lower_a_tilde).should == -1
     upper_a_umlaut.casecmp(lower_a_umlaut).should == -1
@@ -46,10 +46,10 @@ describe "Symbol#casecmp with Symbol" do
     lower_a_umlaut.casecmp(upper_a_umlaut).should == 1
 
     # -- UTF-8 --
-    upper_a_tilde  = :"\xC3\x83"
-    upper_a_umlaut = :"\xC3\x84"
-    lower_a_tilde  = :"\xC3\xA3"
-    lower_a_umlaut = :"\xC3\xA4"
+    upper_a_tilde  = :"Ã"
+    lower_a_tilde  = :"ã"
+    upper_a_umlaut = :"Ä"
+    lower_a_umlaut = :"ä"
 
     upper_a_tilde.casecmp(lower_a_tilde).should == -1
     upper_a_umlaut.casecmp(lower_a_umlaut).should == -1
@@ -72,3 +72,75 @@ describe "Symbol#casecmp" do
     :abc.casecmp(obj).should be_nil
   end
 end
+
+ruby_version_is "2.4" do
+  describe 'Symbol#casecmp?' do
+    it "compares symbols without regard to case" do
+      :abcdef.casecmp?(:abcde).should == false
+      :aBcDeF.casecmp?(:abcdef).should == true
+      :abcdef.casecmp?(:abcdefg).should == false
+      :abcdef.casecmp?(:ABCDEF).should == true
+    end
+
+    it "doesn't consider non-ascii characters equal that aren't" do
+      # -- Latin-1 --
+      upper_a_tilde  = "\xC3".b.to_sym
+      upper_a_umlaut = "\xC4".b.to_sym
+      lower_a_tilde  = "\xE3".b.to_sym
+      lower_a_umlaut = "\xE4".b.to_sym
+
+      lower_a_tilde.casecmp?(lower_a_umlaut).should_not == true
+      lower_a_umlaut.casecmp?(lower_a_tilde).should_not == true
+      upper_a_tilde.casecmp?(upper_a_umlaut).should_not == true
+      upper_a_umlaut.casecmp?(upper_a_tilde).should_not == true
+
+      # -- UTF-8 --
+      upper_a_tilde  = :"Ã"
+      lower_a_tilde  = :"ã"
+      upper_a_umlaut = :"Ä"
+      lower_a_umlaut = :"ä"
+
+      lower_a_tilde.casecmp?(lower_a_umlaut).should_not == true
+      lower_a_umlaut.casecmp?(lower_a_tilde).should_not == true
+      upper_a_tilde.casecmp?(upper_a_umlaut).should_not == true
+      upper_a_umlaut.casecmp?(upper_a_tilde).should_not == true
+    end
+
+    it "doesn't do case mapping for non-ascii and non-unicode characters" do
+      # -- Latin-1 --
+      upper_a_tilde  = "\xC3".b.to_sym
+      upper_a_umlaut = "\xC4".b.to_sym
+      lower_a_tilde  = "\xE3".b.to_sym
+      lower_a_umlaut = "\xE4".b.to_sym
+
+      upper_a_tilde.casecmp?(lower_a_tilde).should == false
+      upper_a_umlaut.casecmp?(lower_a_umlaut).should == false
+      lower_a_tilde.casecmp?(upper_a_tilde).should == false
+      lower_a_umlaut.casecmp?(upper_a_umlaut).should == false
+    end
+
+    it 'does case mapping for unicode characters' do
+      # -- UTF-8 --
+      upper_a_tilde  = :"Ã"
+      lower_a_tilde  = :"ã"
+      upper_a_umlaut = :"Ä"
+      lower_a_umlaut = :"ä"
+
+      upper_a_tilde.casecmp?(lower_a_tilde).should == true
+      upper_a_umlaut.casecmp?(lower_a_umlaut).should == true
+      lower_a_tilde.casecmp?(upper_a_tilde).should == true
+      lower_a_umlaut.casecmp?(upper_a_umlaut).should == true
+    end
+
+    it 'returns nil when comparing characters with different encodings' do
+      # -- Latin-1 --
+      upper_a_tilde = "\xC3".b.to_sym
+
+      # -- UTF-8 --
+      lower_a_tilde = :"ã"
+
+      upper_a_tilde.casecmp?(lower_a_tilde).should == nil
+      lower_a_tilde.casecmp?(upper_a_tilde).should == nil
+    end
+  end
+end

spec/ruby/core/symbol/downcase_spec.rb

@@ -20,6 +20,13 @@ describe "Symbol#downcase" do
     end
   end
 
+  ruby_version_is '2.4' do
+    it "uncapitalizes all Unicode characters" do
+      "ÄÖÜ".to_sym.downcase.should == :"äöü"
+      "AOU".to_sym.downcase.should == :"aou"
+    end
+  end
+
   it "leaves non-alphabetic ASCII characters as they were" do
     "Glark?!?".to_sym.downcase.should == :"glark?!?"
   end

spec/ruby/core/symbol/dup_spec.rb

@@ -0,0 +1,9 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is '2.4' do
+  describe "Symbol#dup" do
+    it "returns self" do
+      :a_symbol.dup.should equal(:a_symbol)
+    end
+  end
+end

spec/ruby/core/symbol/swapcase_spec.rb

@@ -28,6 +28,13 @@ describe "Symbol#swapcase" do
     end
   end
 
+  ruby_version_is '2.4' do
+    it "swaps the case for Unicode characters" do
+      "äÖü".to_sym.swapcase.should == :"ÄöÜ"
+      "aOu".to_sym.swapcase.should == :"AoU"
+    end
+  end
+
   it "leaves non-alphabetic ASCII characters as they were" do
     "Glark?!?".to_sym.swapcase.should == :"gLARK?!?"
   end

spec/ruby/core/symbol/upcase_spec.rb

@@ -16,6 +16,13 @@ describe "Symbol#upcase" do
     end
   end
 
+  ruby_version_is '2.4' do
+    it "capitalizes all Unicode characters" do
+      "äöü".to_sym.upcase.should == :"ÄÖÜ"
+      "aou".to_sym.upcase.should == :"AOU"
+    end
+  end
+
   it "leaves non-alphabetic ASCII characters as they were" do
     "Glark?!?".to_sym.upcase.should == :"GLARK?!?"
   end

spec/ruby/core/thread/element_set_spec.rb

@@ -9,12 +9,12 @@ describe "Thread#[]=" do
   it "raises a RuntimeError if the thread is frozen" do
     running = false
     t = Thread.new do
-      Thread.pass until running
       t.freeze
-      t[:foo] = "bar"
+      -> {
+        t[:foo] = "bar"
+      }.should raise_error(RuntimeError, /frozen/)
     end
-    running = true
-    lambda { t.join }.should raise_error(RuntimeError)
+    t.join
   end
 
   it "raises exceptions on the wrong type of keys" do

spec/ruby/core/thread/fixtures/classes.rb

@@ -120,7 +120,10 @@ module ThreadSpecs
   end
 
   def self.status_of_thread_with_uncaught_exception
-    t = Thread.new { raise "error" }
+    t = Thread.new {
+      Thread.current.report_on_exception = false
+      raise "error"
+    }
     begin
       t.join
     rescue RuntimeError
@@ -159,6 +162,7 @@ module ThreadSpecs
 
   def self.dying_thread_ensures(kill_method_name=:kill)
     Thread.new do
+      Thread.current.report_on_exception = false
       begin
         Thread.current.send(kill_method_name)
       ensure
@@ -169,6 +173,7 @@ module ThreadSpecs
 
   def self.dying_thread_with_outer_ensure(kill_method_name=:kill)
     Thread.new do
+      Thread.current.report_on_exception = false
       begin
         begin
           Thread.current.send(kill_method_name)

spec/ruby/core/thread/join_spec.rb

@@ -46,7 +46,10 @@ describe "Thread#join" do
   end
 
   it "raises any exceptions encountered in the thread body" do
-    t = Thread.new { raise NotImplementedError.new("Just kidding") }
+    t = Thread.new {
+      Thread.current.report_on_exception = false
+      raise NotImplementedError.new("Just kidding")
+    }
     lambda { t.join }.should raise_error(NotImplementedError)
   end
 

spec/ruby/core/thread/key_spec.rb

@@ -9,7 +9,7 @@ describe "Thread#key?" do
     @th.join
   end
 
-  it "tests for existance of thread local variables using symbols or strings" do
+  it "tests for existence of thread local variables using symbols or strings" do
     @th.key?(:oliver).should == true
     @th.key?("oliver").should == true
     @th.key?(:stanley).should == false

spec/ruby/core/thread/raise_spec.rb

@@ -51,6 +51,7 @@ describe "Thread#raise on a sleeping thread" do
 
   it "is captured and raised by Thread#value" do
     t = Thread.new do
+      Thread.current.report_on_exception = false
       sleep
     end
 
@@ -62,6 +63,7 @@ describe "Thread#raise on a sleeping thread" do
 
   it "raises a RuntimeError when called with no arguments inside rescue" do
     t = Thread.new do
+      Thread.current.report_on_exception = false
       begin
         1/0
       rescue ZeroDivisionError
@@ -113,6 +115,7 @@ describe "Thread#raise on a running thread" do
 
   it "can go unhandled" do
     t = Thread.new do
+      Thread.current.report_on_exception = false
       loop { Thread.pass }
     end
 
@@ -123,6 +126,7 @@ describe "Thread#raise on a running thread" do
   it "raises the given argument even when there is an active exception" do
     raised = false
     t = Thread.new do
+      Thread.current.report_on_exception = false
       begin
         1/0
       rescue ZeroDivisionError
@@ -142,6 +146,7 @@ describe "Thread#raise on a running thread" do
   it "raises a RuntimeError when called with no arguments inside rescue" do
     raised = false
     t = Thread.new do
+      Thread.current.report_on_exception = false
       begin
         1/0
       rescue ZeroDivisionError
@@ -164,6 +169,7 @@ describe "Thread#raise on same thread" do
 
   it "raises a RuntimeError when called with no arguments inside rescue" do
     t = Thread.new do
+      Thread.current.report_on_exception = false
       begin
         1/0
       rescue ZeroDivisionError

spec/ruby/core/thread/report_on_exception_spec.rb

@@ -0,0 +1,102 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+ruby_version_is "2.4" do
+  describe "Thread.report_on_exception" do
+    it "defaults to false" do
+      ruby_exe("p Thread.report_on_exception").should == "false\n"
+    end
+  end
+
+  describe "Thread.report_on_exception=" do
+    before :each do
+      @report_on_exception = Thread.report_on_exception
+    end
+
+    after :each do
+      Thread.report_on_exception = @report_on_exception
+    end
+
+    it "changes the default value for new threads" do
+      Thread.report_on_exception = true
+      Thread.report_on_exception.should == true
+      t = Thread.new {}
+      t.join
+      t.report_on_exception.should == true
+    end
+  end
+
+  describe "Thread#report_on_exception" do
+    it "returns whether the Thread will print a backtrace if it exits with an exception" do
+      t = Thread.new { Thread.current.report_on_exception = true }
+      t.join
+      t.report_on_exception.should == true
+
+      t = Thread.new { Thread.current.report_on_exception = false }
+      t.join
+      t.report_on_exception.should == false
+    end
+  end
+
+  describe "Thread#report_on_exception=" do
+    describe "when set to true" do
+      it "prints a backtrace on $stderr if it terminates with an exception" do
+        t = nil
+        -> {
+          t = Thread.new {
+            Thread.current.report_on_exception = true
+            raise RuntimeError, "Thread#report_on_exception specs"
+          }
+          Thread.pass while t.alive?
+        }.should output("", /Thread.+terminated with exception.+Thread#report_on_exception specs/m)
+
+        -> {
+          t.join
+        }.should raise_error(RuntimeError, "Thread#report_on_exception specs")
+      end
+    end
+
+    describe "when set to false" do
+      it "lets the thread terminates silently with an exception" do
+        t = nil
+        -> {
+          t = Thread.new {
+            Thread.current.report_on_exception = false
+            raise RuntimeError, "Thread#report_on_exception specs"
+          }
+          Thread.pass while t.alive?
+        }.should output("", "")
+
+        -> {
+          t.join
+        }.should raise_error(RuntimeError, "Thread#report_on_exception specs")
+      end
+    end
+
+    ruby_bug "#13163", "2.4"..."2.5" do
+      describe "when used in conjunction with Thread#abort_on_exception" do
+        it "first reports then send the exception back to the main Thread" do
+          t = nil
+          mutex = Mutex.new
+          mutex.lock
+          -> {
+            t = Thread.new {
+              Thread.current.abort_on_exception = true
+              Thread.current.report_on_exception = true
+              mutex.lock
+              mutex.unlock
+              raise RuntimeError, "Thread#report_on_exception specs"
+            }
+
+            -> {
+              mutex.sleep(5)
+            }.should raise_error(RuntimeError, "Thread#report_on_exception specs")
+          }.should output("", /Thread.+terminated with exception.+Thread#report_on_exception specs/m)
+
+          -> {
+            t.join
+          }.should raise_error(RuntimeError, "Thread#report_on_exception specs")
+        end
+      end
+    end
+  end
+end

spec/ruby/core/thread/shared/exit.rb

@@ -112,7 +112,7 @@ describe :thread_exit, shared: true do
 
   quarantine! do
 
-    it "propogates inner exception to Thread.join if there is an outer ensure clause" do
+    it "propagates inner exception to Thread.join if there is an outer ensure clause" do
       thread = ThreadSpecs.dying_thread_with_outer_ensure(@method) { }
       lambda { thread.join }.should raise_error(RuntimeError, "In dying thread")
     end

spec/ruby/core/thread/value_spec.rb

@@ -7,7 +7,10 @@ describe "Thread#value" do
   end
 
   it "re-raises an error for an uncaught exception" do
-    t = Thread.new { raise "Hello" }
+    t = Thread.new {
+      Thread.current.report_on_exception = false
+      raise "Hello"
+    }
     lambda { t.value }.should raise_error(RuntimeError, "Hello")
   end