Update to ruby/spec@e81b3cd

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67361 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

53 files changed, 932 insertions, 106 deletions

diff --git a/spec/ruby/.mspec.constants b/spec/ruby/.mspec.constants
index 6347a0c701..44f0011df9 100644
--- a/spec/ruby/.mspec.constants
+++ b/spec/ruby/.mspec.constants
@@ -88,7 +88,6 @@ IncludeSpecsClass
 IncludeSpecsMiddle
 IncludeSpecsTop
 IncludesMath
-InvalidTostrTest
 JSON
 KSAutoloadA
 KSAutoloadB
@@ -177,6 +176,7 @@ StringRefinement
 StringScanner
 StringSubclass
 StructClasses
+Syck
 Syslog
 TCPServer
 TCPSocket
@@ -205,7 +205,6 @@ UserObject
 UserPreviouslyDefinedWithInitializedIvar
 UserRegexp
 UserString
-ValidTostrTest
 Vector
 WEBrick
 WIN32OLE
diff --git a/spec/ruby/.rubocop.yml b/spec/ruby/.rubocop.yml
index 58529f15b2..5de7154442 100644
--- a/spec/ruby/.rubocop.yml
+++ b/spec/ruby/.rubocop.yml
@@ -96,3 +96,7 @@ Lint/UnreachableCode:
 Lint/UriRegexp:
   Exclude:
     - 'library/uri/regexp_spec.rb'
+
+Lint/Debugger:
+  Exclude:
+    - 'core/binding/fixtures/irb.rb'
diff --git a/spec/ruby/.travis.yml b/spec/ruby/.travis.yml
index 779fe5ba2a..11bd7a55fd 100644
--- a/spec/ruby/.travis.yml
+++ b/spec/ruby/.travis.yml
@@ -6,14 +6,14 @@ script:
   - ../mspec/bin/mspec $MSPEC_OPTS
 matrix:
   include:
-    - rvm: 2.5.3
+    - rvm: 2.5.5
       env: MSPEC_OPTS="-R2 -ff"
     - rvm: 2.3.8
     - rvm: 2.4.5
       env: CHECK_LEAKS=true
-    - rvm: 2.5.3
+    - rvm: 2.5.5
       env: CHECK_LEAKS=true
-    - rvm: 2.6.1
+    - rvm: 2.6.2
       env: CHECK_LEAKS=true
     - env: RUBOCOP=true
       rvm: 2.4.5
diff --git a/spec/ruby/command_line/dash_upper_c_spec.rb b/spec/ruby/command_line/dash_upper_c_spec.rb
index 761beaadab..ece1b32105 100644
--- a/spec/ruby/command_line/dash_upper_c_spec.rb
+++ b/spec/ruby/command_line/dash_upper_c_spec.rb
@@ -1,23 +1,6 @@
 require_relative '../spec_helper'
+require_relative 'shared/change_directory'
 
-describe 'The -C command line option' do
-  before :all do
-    @script  = fixture(__FILE__, 'dash_upper_c_script.rb')
-    @tempdir = File.dirname(@script)
-  end
-
-  it 'changes the PWD when using a file' do
-    output = ruby_exe(@script, options: "-C #{@tempdir}")
-    output.should == @tempdir
-  end
-
-  it 'does not need a space after -C for the argument' do
-    output = ruby_exe(@script, options: "-C#{@tempdir}")
-    output.should == @tempdir
-  end
-
-  it 'changes the PWD when using -e' do
-    output = ruby_exe(nil, options: "-C #{@tempdir} -e 'print Dir.pwd'")
-    output.should == @tempdir
-  end
+describe "The -C command line option" do
+  it_behaves_like :command_line_change_directory, "-C"
 end
diff --git a/spec/ruby/command_line/dash_upper_x_spec.rb b/spec/ruby/command_line/dash_upper_x_spec.rb
new file mode 100644
index 0000000000..8ef9aae4b1
--- /dev/null
+++ b/spec/ruby/command_line/dash_upper_x_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../spec_helper'
+require_relative 'shared/change_directory'
+
+describe "The -X command line option" do
+  it_behaves_like :command_line_change_directory, "-X"
+end
diff --git a/spec/ruby/command_line/feature_spec.rb b/spec/ruby/command_line/feature_spec.rb
new file mode 100644
index 0000000000..fa2a82cb4b
--- /dev/null
+++ b/spec/ruby/command_line/feature_spec.rb
@@ -0,0 +1,65 @@
+require_relative '../spec_helper'
+
+describe "The --enable and --disable flags" do
+
+  it "can be used with gems" do
+    ruby_exe("p defined?(Gem)", options: "--enable=gems").chomp.should == "\"constant\""
+    ruby_exe("p defined?(Gem)", options: "--disable=gems").chomp.should == "nil"
+    ruby_exe("p defined?(Gem)", options: "--enable-gems").chomp.should == "\"constant\""
+    ruby_exe("p defined?(Gem)", options: "--disable-gems").chomp.should == "nil"
+  end
+
+  it "can be used with gem" do
+    ruby_exe("p defined?(Gem)", options: "--enable=gem").chomp.should == "\"constant\""
+    ruby_exe("p defined?(Gem)", options: "--disable=gem").chomp.should == "nil"
+    ruby_exe("p defined?(Gem)", options: "--enable-gem").chomp.should == "\"constant\""
+    ruby_exe("p defined?(Gem)", options: "--disable-gem").chomp.should == "nil"
+  end
+
+  it "can be used with did_you_mean" do
+    ruby_exe("p defined?(DidYouMean)", options: "--enable=did_you_mean").chomp.should == "\"constant\""
+    ruby_exe("p defined?(DidYouMean)", options: "--disable=did_you_mean").chomp.should == "nil"
+    ruby_exe("p defined?(DidYouMean)", options: "--enable-did_you_mean").chomp.should == "\"constant\""
+    ruby_exe("p defined?(DidYouMean)", options: "--disable-did_you_mean").chomp.should == "nil"
+  end
+
+  it "can be used with rubyopt" do
+    ruby_exe("p $VERBOSE", options: "--enable=rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "true"
+    ruby_exe("p $VERBOSE", options: "--disable=rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "false"
+    ruby_exe("p $VERBOSE", options: "--enable-rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "true"
+    ruby_exe("p $VERBOSE", options: "--disable-rubyopt", env: {'RUBYOPT' => '-w'}).chomp.should == "false"
+  end
+
+  it "can be used with frozen-string-literal" do
+    ruby_exe("p 'foo'.frozen?", options: "--enable=frozen-string-literal").chomp.should == "true"
+    ruby_exe("p 'foo'.frozen?", options: "--disable=frozen-string-literal").chomp.should == "false"
+    ruby_exe("p 'foo'.frozen?", options: "--enable-frozen-string-literal").chomp.should == "true"
+    ruby_exe("p 'foo'.frozen?", options: "--disable-frozen-string-literal").chomp.should == "false"
+  end
+
+  ruby_version_is "2.6" do
+    it "can be used with jit" do
+      ruby_exe("p RubyVM::MJIT.enabled?", options: "--enable=jit").chomp.should == "true"
+      ruby_exe("p RubyVM::MJIT.enabled?", options: "--disable=jit").chomp.should == "false"
+      ruby_exe("p RubyVM::MJIT.enabled?", options: "--enable-jit").chomp.should == "true"
+      ruby_exe("p RubyVM::MJIT.enabled?", options: "--disable-jit").chomp.should == "false"
+    end
+  end
+
+  it "can be used with all" do
+    e = "p [defined?(Gem), defined?(DidYouMean), $VERBOSE, 'foo'.frozen?]"
+    env = {'RUBYOPT' => '-w'}
+    ruby_exe(e, options: "--enable=all", env: env).chomp.should == "[\"constant\", \"constant\", true, true]"
+    ruby_exe(e, options: "--enable-all", env: env).chomp.should == "[\"constant\", \"constant\", true, true]"
+    ruby_exe(e, options: "--disable=all", env: env).chomp.should == "[nil, nil, false, false]"
+    ruby_exe(e, options: "--disable-all", env: env).chomp.should == "[nil, nil, false, false]"
+  end
+
+  it "prints a warning for unknown features" do
+    ruby_exe("p 14", options: "--enable=ruby-spec-feature-does-not-exist 2>&1").chomp.should include('warning: unknown argument for --enable')
+    ruby_exe("p 14", options: "--disable=ruby-spec-feature-does-not-exist 2>&1").chomp.should include('warning: unknown argument for --disable')
+    ruby_exe("p 14", options: "--enable-ruby-spec-feature-does-not-exist 2>&1").chomp.should include('warning: unknown argument for --enable')
+    ruby_exe("p 14", options: "--disable-ruby-spec-feature-does-not-exist 2>&1").chomp.should include('warning: unknown argument for --disable')
+  end
+
+end
diff --git a/spec/ruby/command_line/fixtures/dash_upper_c_script.rb b/spec/ruby/command_line/fixtures/change_directory_script.rb
index abe244705f..abe244705f 100644
--- a/spec/ruby/command_line/fixtures/dash_upper_c_script.rb
+++ b/spec/ruby/command_line/fixtures/change_directory_script.rb
diff --git a/spec/ruby/command_line/rubylib_spec.rb b/spec/ruby/command_line/rubylib_spec.rb
index 20e9c2cf95..b45919b997 100644
--- a/spec/ruby/command_line/rubylib_spec.rb
+++ b/spec/ruby/command_line/rubylib_spec.rb
@@ -30,6 +30,7 @@ describe "The RUBYLIB environment variable" do
     dir = tmp("rubylib/incl_front")
     ENV["RUBYLIB"] = @pre + dir
     paths = ruby_exe("puts $LOAD_PATH").lines.map(&:chomp)
+    paths.shift if paths.first.end_with?('/gem-rehash')
     if PlatformGuard.implementation? :ruby
       # In a MRI checkout, $PWD and some extra -I entries end up as
       # the first entries in $LOAD_PATH. So just assert that it's not last.
diff --git a/spec/ruby/command_line/shared/change_directory.rb b/spec/ruby/command_line/shared/change_directory.rb
new file mode 100644
index 0000000000..9cb6e90ac6
--- /dev/null
+++ b/spec/ruby/command_line/shared/change_directory.rb
@@ -0,0 +1,21 @@
+describe :command_line_change_directory, shared: true do
+  before :all do
+    @script  = fixture(__FILE__, 'change_directory_script.rb')
+    @tempdir = File.dirname(@script)
+  end
+
+  it 'changes the PWD when using a file' do
+    output = ruby_exe(@script, options: "#{@method} #{@tempdir}")
+    output.should == @tempdir
+  end
+
+  it 'does not need a space after -C for the argument' do
+    output = ruby_exe(@script, options: "#{@method}#{@tempdir}")
+    output.should == @tempdir
+  end
+
+  it 'changes the PWD when using -e' do
+    output = ruby_exe(nil, options: "#{@method} #{@tempdir} -e 'print Dir.pwd'")
+    output.should == @tempdir
+  end
+end
diff --git a/spec/ruby/core/binding/fixtures/irb.rb b/spec/ruby/core/binding/fixtures/irb.rb
new file mode 100644
index 0000000000..5f305f2d5d
--- /dev/null
+++ b/spec/ruby/core/binding/fixtures/irb.rb
@@ -0,0 +1,3 @@
+a = 10
+
+binding.irb
diff --git a/spec/ruby/core/binding/irb_spec.rb b/spec/ruby/core/binding/irb_spec.rb
new file mode 100644
index 0000000000..dd3df0b28a
--- /dev/null
+++ b/spec/ruby/core/binding/irb_spec.rb
@@ -0,0 +1,17 @@
+require_relative '../../spec_helper'
+
+ruby_version_is "2.5" do
+  describe "Binding#irb" do
+    it "creates an IRB session with the binding in scope" do
+      irb_fixture = fixture __FILE__, "irb.rb"
+
+      out = IO.popen([*ruby_exe, irb_fixture], "r+") do |pipe|
+        pipe.puts "a ** 2"
+        pipe.puts "exit"
+        pipe.readlines.map(&:chomp)
+      end
+
+      out[-3..-1].should == ["a ** 2", "100", "exit"]
+    end
+  end
+end
diff --git a/spec/ruby/core/file/mtime_spec.rb b/spec/ruby/core/file/mtime_spec.rb
index d5769c0584..c5d854bb08 100644
--- a/spec/ruby/core/file/mtime_spec.rb
+++ b/spec/ruby/core/file/mtime_spec.rb
@@ -12,7 +12,7 @@ describe "File.mtime" do
 
   it "returns the modification Time of the file" do
     File.mtime(@filename).should be_kind_of(Time)
-    File.mtime(@filename).should be_close(@mtime, 2.0)
+    File.mtime(@filename).should be_close(@mtime, 60.0)
   end
 
   guard -> { platform_is :linux or (platform_is :windows and ruby_version_is '2.5') } do
diff --git a/spec/ruby/core/float/to_s_spec.rb b/spec/ruby/core/float/to_s_spec.rb
index 58a58549ed..127132b567 100644
--- a/spec/ruby/core/float/to_s_spec.rb
+++ b/spec/ruby/core/float/to_s_spec.rb
@@ -75,11 +75,11 @@ describe "Float#to_s" do
     -10000000000000000.0.to_s.should == "-1.0e+16"
   end
 
-  it "uses non-e format for a positive value with whole part having 17 significant figures" do
+  it "uses e format for a positive value with whole part having 17 significant figures" do
     1000000000000000.0.to_s.should == "1.0e+15"
   end
 
-  it "uses non-e format for a negative value with whole part having 17 significant figures" do
+  it "uses e format for a negative value with whole part having 17 significant figures" do
     -1000000000000000.0.to_s.should == "-1.0e+15"
   end
 
@@ -95,6 +95,201 @@ describe "Float#to_s" do
   it "outputs the minimal, unique form to represent the value" do
     0.56.to_s.should == "0.56"
   end
+
+  describe "matches" do
+    ruby_version_is "2.4" do # For unpack1
+      it "random examples in all ranges" do
+        # 50.times do
+        #   bytes = (0...8).map { rand(256) }
+        #   string = bytes.pack('C8')
+        #   float = string.unpack('D').first
+        #   puts "      #{bytes.pack('C8').inspect}.unpack1('D').to_s.should == #{float.to_s.inspect}"
+        # end
+
+        "\x97\x15\xC1| \xF5\x19\xAD".unpack1('D').to_s.should == "-1.9910613439044092e-91"
+        "\xBF\xF0\x14\xAD\xDF\x17q\xD1".unpack1('D').to_s.should == "-2.075408637901046e+84"
+        "\xDF\xBD\xC0\x89\xDA\x1F&$".unpack1('D').to_s.should == "1.5219626883645564e-134"
+        "|0<?a\xFB\xBFG".unpack1('D').to_s.should == "4.251130678455814e+37"
+        "U\xEE*\xB7\xF1\xB8\xE7\x18".unpack1('D').to_s.should == "1.0648588700899858e-188"
+        "\x15Y\xD1J\x80/7\xD0".unpack1('D').to_s.should == "-2.6847034291392176e+78"
+        "\x1D\x1E\xD2\x9A3)\xF5q".unpack1('D').to_s.should == "8.818842365424256e+240"
+        "M\xD0C\xA3\x19-\xE3\xE5".unpack1('D').to_s.should == "-6.365746090981858e+182"
+        "\xAFf\xFE\xF0$\x85\x01L".unpack1('D').to_s.should == "1.374692728674642e+58"
+        "'N\xB7\x12\xE0\xC8t\t".unpack1('D').to_s.should == "4.1254080603298014e-263"
+        "\xAFn\xF2x\x85\xB5\x15j".unpack1('D').to_s.should == "1.0635019031720867e+203"
+        "nQ\x95\xFA\xD9\xE3\xC5)".unpack1('D').to_s.should == "1.8641386367625094e-107"
+        "\xC2\x9A\xB1|/\xCAJM".unpack1('D').to_s.should == "2.204135837758401e+64"
+        "q n\xD8\x86\xF2\xA8D".unpack1('D').to_s.should == "5.890531214599543e+22"
+        "dmR\xC6\xB3\xF3\x95G".unpack1('D').to_s.should == "7.294790578028111e+36"
+        "6I\x0E)?E\xB5\xE1".unpack1('D').to_s.should == "-4.7847061687992665e+162"
+        "\xCD\xE0\xBBy\x9F\xD8\xE89".unpack1('D').to_s.should == "9.800091365433584e-30"
+        "\xB8\x98TN\x98\xEE\xC1\xF9".unpack1('D').to_s.should == "-3.178740061599073e+278"
+        "\x8F_\xFF\x15\x1F2\x17B".unpack1('D').to_s.should == "24906286463.84332"
+        "\x94\x18V\xC5&\xE6\xEAi".unpack1('D').to_s.should == "1.6471900588998988e+202"
+        "\xECq\xB1\x01\ai\xBD,".unpack1('D').to_s.should == "3.5248469410018065e-93"
+        "\x9C\xC6\x13pG\xDAx\x9A".unpack1('D').to_s.should == "-3.743306318201459e-181"
+        "\xEA7,gJ\xEE\x8E*".unpack1('D').to_s.should == "1.0789044330549825e-103"
+        "1\xD3\xF5K\x8D\xEF\xA7\r".unpack1('D').to_s.should == "7.011009309284311e-243"
+        "o\xB3\x02\xAF\x9D\xFC\r\xF6".unpack1('D').to_s.should == "-4.610585875652112e+260"
+        "&:x\x15\xFC3P\x01".unpack1('D').to_s.should == "2.362770515774595e-302"
+        "\xE6<C\xB8\x90\xF2\xCF\x90".unpack1('D').to_s.should == "-1.0535871178808475e-227"
+        "\x9Al\aB6's}".unpack1('D').to_s.should == "1.957205609213647e+296"
+        "+\v\x16\xFD\x19\x0E\x9B\x06".unpack1('D').to_s.should == "7.631200870990123e-277"
+        "\xEC\xF8~\xDA\xE7Tf\x92".unpack1('D').to_s.should == "-4.942358450191624e-220"
+        "\xE0\xA0\xC9\x906\xBDcI".unpack1('D').to_s.should == "3.521575588133954e+45"
+        "\xBD\xFD\xC9\xFD\rp\x02\x0F".unpack1('D').to_s.should == "2.2651682962118346e-236"
+        "\xE9\xA8\xAD\xC4\xF6u\xF7\x19".unpack1('D').to_s.should == "1.3803378872547194e-183"
+        "\"f\xED9\x17\xF0\xF1!".unpack1('D').to_s.should == "3.591307506787987e-145"
+        "\xE6\xF2\xB6\x9CFl\xB3O".unpack1('D').to_s.should == "8.785250953340842e+75"
+        "g\xFD\xEA\r~x\xBA\x9D".unpack1('D').to_s.should == "-1.7955908504285607e-165"
+        "\xE2\x84J\xC7\x00\n/\x06".unpack1('D').to_s.should == "6.839790344291208e-279"
+        "s\xFB\xA58x\xF1\xA9\xD9".unpack1('D').to_s.should == "-8.574967051032431e+123"
+        "\xE2\x9D\xBE\xE2\x10k{\xFC".unpack1('D').to_s.should == "-4.2751876153404507e+291"
+        "!z \xB4i4\x8C5".unpack1('D').to_s.should == "9.423078517655126e-51"
+        "!_\xEAp- 7R".unpack1('D').to_s.should == "1.1500944673871687e+88"
+        "\x03\xAD=\\\xCB >\xBB".unpack1('D').to_s.should == "-2.4921382721208654e-23"
+        "\x94\x01\xB1\x87\x10\x9B#\x88".unpack1('D').to_s.should == "-1.8555672851958583e-269"
+        "\x90H\xFF\\S\x01)\x89".unpack1('D').to_s.should == "-1.5509713490195968e-264"
+        "HW@\x13\x85&=)".unpack1('D').to_s.should == "4.848496966571536e-110"
+        "\x14\xDB\\\x10\x93\x9C\xD66".unpack1('D').to_s.should == "1.5842813502410472e-44"
+        "\x9D8p>\xFF\x9B[\xF3".unpack1('D').to_s.should == "-4.826061446912647e+247"
+        "c\x9D}\t]\xF9pg".unpack1('D').to_s.should == "1.8907034486212682e+190"
+        "\xA51\xC9WJ\xB5a^".unpack1('D').to_s.should == "4.422435231445608e+146"
+        "\x8BL\x90\xCB\xEARf\f".unpack1('D').to_s.should == "6.235963569982745e-249"
+      end
+
+      it "random examples in human ranges" do
+        # 50.times do
+        #   formatted = ''
+        #   rand(1..3).times do
+        #     formatted << rand(10).to_s
+        #   end
+        #   formatted << '.'
+        #   rand(1..9).times do
+        #     formatted << rand(10).to_s
+        #   end
+        #   float = formatted.to_f
+        #   string = [float].pack('D')
+        #   puts "      #{string.inspect}.unpack1('D').to_s.should == #{float.to_s.inspect}"
+        # end
+
+        ";\x01M\x84\r\xF7M@".unpack1('D').to_s.should == "59.9301"
+        "\xAE\xD3HKe|\x8A@".unpack1('D').to_s.should == "847.54946"
+        "/\xDD$\x06\x81u8@".unpack1('D').to_s.should == "24.459"
+        "E\xD8\xF0\xF4JY\xF0?".unpack1('D').to_s.should == "1.0218"
+        "[\brP\xC2\xCC\x05@".unpack1('D').to_s.should == "2.72498"
+        "\xE6w\x9A\xCCx\xF6T@".unpack1('D').to_s.should == "83.851123"
+        "\xB4\xD4&\xC0C\xFD.@".unpack1('D').to_s.should == "15.494657521"
+        "\xCD\xCC\xCC\xCC\xCCLM@".unpack1('D').to_s.should == "58.6"
+        "\xA1\x84\x99\xB6\x7F\xE5\x13@".unpack1('D').to_s.should == "4.97412"
+        "\xD7\xA3p=\n\x9C\x80@".unpack1('D').to_s.should == "531.505"
+        "S\x96!\x8E\xF5\x0E\x8F@".unpack1('D').to_s.should == "993.8699"
+        "\xF1F\xE6\x91?\x18\xD7?".unpack1('D').to_s.should == "0.360855"
+        "=\n\xD7\xA3p=\x15@".unpack1('D').to_s.should == "5.31"
+        "\x90Ci\x147\xC74@".unpack1('D').to_s.should == "20.7781842"
+        "A\ft\xED\v\xE8\xB9?".unpack1('D').to_s.should == "0.101197"
+        "\x9A\x99\x99\x99\x999T@".unpack1('D').to_s.should == "80.9"
+        "\x00\x00\x00\x00\x00\x00\x1A@".unpack1('D').to_s.should == "6.5"
+        "\xD3J\xC6\xD6\x98\x8Es@".unpack1('D').to_s.should == "312.9123142"
+        "SQ\xE5I\fQ\x1E@".unpack1('D').to_s.should == "7.57914844"
+        "k]Q\xE7\xDDb\x1E@".unpack1('D').to_s.should == "7.59654962"
+        "\x1F\x85\xEBQ\xB8\xEAz@".unpack1('D').to_s.should == "430.67"
+        "\x00\x00\x00\x00\x00\x00\x14@".unpack1('D').to_s.should == "5.0"
+        "{\x14\xAEG\xE1\n}@".unpack1('D').to_s.should == "464.68"
+        "\x12\x83\xC0\xCA\xA1=V@".unpack1('D').to_s.should == "88.963"
+        "\x9Aw\x9C\xA2#y\e@".unpack1('D').to_s.should == "6.8683"
+        "(\x0F\v\xB5\xA6y\xFB?".unpack1('D').to_s.should == "1.7172"
+        "\xD5x\xE9&1H!@".unpack1('D').to_s.should == "8.641"
+        "w'Deh\x1Ab@".unpack1('D').to_s.should == "144.8252436"
+        ":X\xFF\xE70_\x04@".unpack1('D').to_s.should == "2.54648"
+        "E4\xB2\x12\x90\xCA\x1E@".unpack1('D').to_s.should == "7.69781522"
+        "fffff\xAA\x80@".unpack1('D').to_s.should == "533.3"
+        "\xCD\x92\x005\xB5p:@".unpack1('D').to_s.should == "26.440265"
+        "\xBE\x1D<nS\x7F\x19@".unpack1('D').to_s.should == "6.3743417"
+        "R\xB8\x1E\x85\xEBYb@".unpack1('D').to_s.should == "146.81"
+        "\x02\x87\xAB^\xD9\xC0\xF4?".unpack1('D').to_s.should == "1.2970823"
+        "\x00\x00\x00\x00\x00\x00\"@".unpack1('D').to_s.should == "9.0"
+        "Zd;\xDFO3\x84@".unpack1('D').to_s.should == "646.414"
+        "\x9A\x99\x99\x99\x99\x99\t@".unpack1('D').to_s.should == "3.2"
+        "\xCD#\x7F0\xF0\xE5i@".unpack1('D').to_s.should == "207.18557"
+        "\xBE\x9F\x1A/\xDD$\xF2?".unpack1('D').to_s.should == "1.134"
+        "\xEE|?5^\xBA\xF3?".unpack1('D').to_s.should == "1.233"
+        "\xB4\xB7\xFE\xD7\x05\x03i@".unpack1('D').to_s.should == "200.094463346"
+        "N\x95\xD6|\xE8HG@".unpack1('D').to_s.should == "46.56959496"
+        "Y\x868\xD6\xC5-!@".unpack1('D').to_s.should == "8.5894"
+        "myE\xED\a;\x12@".unpack1('D').to_s.should == "4.557647426"
+        "\xA7s\xEAo\xAE\x96B@".unpack1('D').to_s.should == "37.1771984"
+        "\x14\x7Fo.\x99\x11|@".unpack1('D').to_s.should == "449.0998978"
+        "\xB2\x9EZ}u\x89;@".unpack1('D').to_s.should == "27.536949"
+        "\xD7\xA3p=\nwY@".unpack1('D').to_s.should == "101.86"
+        "\xF3\xE6p\xAD\xF6\xC3x@".unpack1('D').to_s.should == "396.247724"
+      end
+    end
+
+    it "random values from divisions" do
+      (1.0 / 7).to_s.should == "0.14285714285714285"
+
+      # 50.times do
+      #    a = rand(10)
+      #    b = rand(10)
+      #    c = rand(10)
+      #    d = rand(10)
+      #    expression = "#{a}.#{b} / #{c}.#{d}"
+      #    puts "      (#{expression}).to_s.should == #{eval(expression).to_s.inspect}"
+      #  end
+
+      (1.1 / 7.1).to_s.should == "0.15492957746478875"
+      (6.5 / 8.8).to_s.should == "0.7386363636363635"
+      (4.8 / 4.3).to_s.should == "1.1162790697674418"
+      (4.0 / 1.9).to_s.should == "2.1052631578947367"
+      (9.1 / 0.8).to_s.should == "11.374999999999998"
+      (5.3 / 7.5).to_s.should == "0.7066666666666667"
+      (2.8 / 1.8).to_s.should == "1.5555555555555554"
+      (2.1 / 2.5).to_s.should == "0.8400000000000001"
+      (3.5 / 6.0).to_s.should == "0.5833333333333334"
+      (4.6 / 0.3).to_s.should == "15.333333333333332"
+      (0.6 / 2.4).to_s.should == "0.25"
+      (1.3 / 9.1).to_s.should == "0.14285714285714288"
+      (0.3 / 5.0).to_s.should == "0.06"
+      (5.0 / 4.2).to_s.should == "1.1904761904761905"
+      (3.0 / 2.0).to_s.should == "1.5"
+      (6.3 / 2.0).to_s.should == "3.15"
+      (5.4 / 6.0).to_s.should == "0.9"
+      (9.6 / 8.1).to_s.should == "1.1851851851851851"
+      (8.7 / 1.6).to_s.should == "5.437499999999999"
+      (1.9 / 7.8).to_s.should == "0.24358974358974358"
+      (0.5 / 2.1).to_s.should == "0.23809523809523808"
+      (9.3 / 5.8).to_s.should == "1.6034482758620692"
+      (2.7 / 8.0).to_s.should == "0.3375"
+      (9.7 / 7.8).to_s.should == "1.2435897435897436"
+      (8.1 / 2.4).to_s.should == "3.375"
+      (7.7 / 2.7).to_s.should == "2.8518518518518516"
+      (7.9 / 1.7).to_s.should == "4.647058823529412"
+      (6.5 / 8.2).to_s.should == "0.7926829268292683"
+      (7.8 / 9.6).to_s.should == "0.8125"
+      (2.2 / 4.6).to_s.should == "0.47826086956521746"
+      (0.0 / 1.0).to_s.should == "0.0"
+      (8.3 / 2.9).to_s.should == "2.8620689655172415"
+      (3.1 / 6.1).to_s.should == "0.5081967213114754"
+      (2.8 / 7.8).to_s.should == "0.358974358974359"
+      (8.0 / 0.1).to_s.should == "80.0"
+      (1.7 / 6.4).to_s.should == "0.265625"
+      (1.8 / 5.4).to_s.should == "0.3333333333333333"
+      (8.0 / 5.8).to_s.should == "1.3793103448275863"
+      (5.2 / 4.1).to_s.should == "1.2682926829268295"
+      (9.8 / 5.8).to_s.should == "1.6896551724137934"
+      (5.4 / 9.5).to_s.should == "0.5684210526315789"
+      (8.4 / 4.9).to_s.should == "1.7142857142857142"
+      (1.7 / 3.5).to_s.should == "0.4857142857142857"
+      (1.2 / 5.1).to_s.should == "0.23529411764705882"
+      (1.4 / 2.0).to_s.should == "0.7"
+      (4.8 / 8.0).to_s.should == "0.6"
+      (9.0 / 2.5).to_s.should == "3.6"
+      (0.2 / 0.6).to_s.should == "0.33333333333333337"
+      (7.8 / 5.2).to_s.should == "1.5"
+      (9.5 / 5.5).to_s.should == "1.7272727272727273"
+    end
+  end
 end
 
 with_feature :encoding do
diff --git a/spec/ruby/core/hash/shared/each.rb b/spec/ruby/core/hash/shared/each.rb
index bf4c569cfc..1d89cfdd39 100644
--- a/spec/ruby/core/hash/shared/each.rb
+++ b/spec/ruby/core/hash/shared/each.rb
@@ -1,4 +1,6 @@
 describe :hash_each, shared: true do
+
+  # This is inconsistent with below, MRI checks the block arity in rb_hash_each_pair()
   it "yields a [[key, value]] Array for each pair to a block expecting |*args|" do
     all_args = []
     { 1 => 2, 3 => 4 }.send(@method) { |*args| all_args << args }
@@ -19,6 +21,21 @@ describe :hash_each, shared: true do
     ary.sort.should == ["a", "b", "c"]
   end
 
+  it "yields 2 values and not an Array of 2 elements" do
+    obj = Object.new
+    def obj.foo(key, value)
+      ScratchPad << key << value
+    end
+
+    ScratchPad.record([])
+    { "a" => 1 }.send(@method, &obj.method(:foo))
+    ScratchPad.recorded.should == ["a", 1]
+
+    ScratchPad.record([])
+    { "a" => 1 }.send(@method, &-> key, value { ScratchPad << key << value })
+    ScratchPad.recorded.should == ["a", 1]
+  end
+
   it "uses the same order as keys() and values()" do
     h = { a: 1, b: 2, c: 3, d: 5 }
     keys = []
diff --git a/spec/ruby/core/io/read_nonblock_spec.rb b/spec/ruby/core/io/read_nonblock_spec.rb
index 3c02f662f6..59f5064922 100644
--- a/spec/ruby/core/io/read_nonblock_spec.rb
+++ b/spec/ruby/core/io/read_nonblock_spec.rb
@@ -77,6 +77,13 @@ describe "IO#read_nonblock" do
     buffer.should == "1"
   end
 
+  it "returns the passed buffer" do
+    buffer = ""
+    @write.write("1")
+    output = @read.read_nonblock(1, buffer)
+    output.should equal(buffer)
+  end
+
   it "raises IOError on closed stream" do
     lambda { IOSpecs.closed_io.read_nonblock(5) }.should raise_error(IOError)
   end
diff --git a/spec/ruby/core/kernel/pp_spec.rb b/spec/ruby/core/kernel/pp_spec.rb
new file mode 100644
index 0000000000..e19dc64caf
--- /dev/null
+++ b/spec/ruby/core/kernel/pp_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+
+ruby_version_is "2.5" do
+  describe "Kernel#pp" do
+    it "lazily loads the 'pp' library and delegates the call to that library" do
+      # Run in child process to ensure 'pp' hasn't been loaded yet.
+      output = ruby_exe("pp [1, 2, 3]")
+      output.should == "[1, 2, 3]\n"
+    end
+  end
+end
diff --git a/spec/ruby/core/kernel/sleep_spec.rb b/spec/ruby/core/kernel/sleep_spec.rb
index 489f4f8410..a510ae3dc1 100644
--- a/spec/ruby/core/kernel/sleep_spec.rb
+++ b/spec/ruby/core/kernel/sleep_spec.rb
@@ -6,16 +6,20 @@ describe "Kernel#sleep" do
     Kernel.should have_private_instance_method(:sleep)
   end
 
+  it "returns an Integer" do
+    sleep(0.001).should be_kind_of(Integer)
+  end
+
   it "accepts a Float" do
-    sleep(0.1).should be_close(0, 2)
+    sleep(0.001).should >= 0
   end
 
   it "accepts a Fixnum" do
-    sleep(0).should be_close(0, 2)
+    sleep(0).should >= 0
   end
 
   it "accepts a Rational" do
-    sleep(Rational(1, 9)).should be_close(0, 2)
+    sleep(Rational(1, 999)).should >= 0
   end
 
   it "raises an ArgumentError when passed a negative duration" do
diff --git a/spec/ruby/core/method/parameters_spec.rb b/spec/ruby/core/method/parameters_spec.rb
index d750f4c221..750abe13d0 100644
--- a/spec/ruby/core/method/parameters_spec.rb
+++ b/spec/ruby/core/method/parameters_spec.rb
@@ -241,4 +241,19 @@ describe "Method#parameters" do
     m = MethodSpecs::Methods.new
     m.method(:writer=).parameters.should == [[:req]]
   end
+
+  it "returns [[:rest]] for core methods with variable-length argument lists" do
+    m = "foo"
+
+    # match takes rest args
+    m.method(:match).parameters.should == [[:rest]]
+
+    # [] takes 1 to 3 args
+    m.method(:[]).parameters.should == [[:rest]]
+  end
+
+  it "returns [[:req]] for each parameter for core methods with fixed-length argument lists" do
+    m = "foo"
+    m.method(:+).parameters.should == [[:req]]
+  end
 end
diff --git a/spec/ruby/core/method/to_proc_spec.rb b/spec/ruby/core/method/to_proc_spec.rb
index 92bd64aaf1..29b7bec2b3 100644
--- a/spec/ruby/core/method/to_proc_spec.rb
+++ b/spec/ruby/core/method/to_proc_spec.rb
@@ -90,4 +90,15 @@ describe "Method#to_proc" do
     array.each(&obj)
     ScratchPad.recorded.should == [[1, 2]]
   end
+
+  it "returns a proc that properly invokes module methods with super" do
+    m1 = Module.new { def foo(ary); ary << :m1; end; }
+    m2 = Module.new { def foo(ary = []); super(ary); ary << :m2; end; }
+    c2 = Class.new do
+      include m1
+      include m2
+    end
+
+    c2.new.method(:foo).to_proc.call.should == %i[m1 m2]
+  end
 end
diff --git a/spec/ruby/core/module/autoload_spec.rb b/spec/ruby/core/module/autoload_spec.rb
index 224d5fd57b..918eb61764 100644
--- a/spec/ruby/core/module/autoload_spec.rb
+++ b/spec/ruby/core/module/autoload_spec.rb
@@ -16,17 +16,28 @@ end
 describe "Module#autoload" do
   before :all do
     @non_existent = fixture __FILE__, "no_autoload.rb"
+
+    # Require RubyGems eagerly, to ensure #require is already the RubyGems
+    # version, before starting #autoload specs which snapshot #require, and
+    # could end up redefining #require as the original core Kernel#require.
+    begin
+      require "rubygems"
+    rescue LoadError
+    end
   end
 
   before :each do
     @loaded_features = $".dup
-    @frozen_module = Module.new.freeze
 
     ScratchPad.clear
+    @remove = []
   end
 
   after :each do
     $".replace @loaded_features
+    @remove.each { |const|
+      ModuleSpecs::Autoload.send :remove_const, const
+    }
   end
 
   it "registers a file to load the first time the named constant is accessed" do
@@ -39,16 +50,29 @@ describe "Module#autoload" do
     ModuleSpecs::Autoload.should have_constant(:B)
   end
 
+  it "can be overridden with a second autoload on the same constant" do
+    ModuleSpecs::Autoload.autoload :Overridden, @non_existent
+    @remove << :Overridden
+    ModuleSpecs::Autoload.autoload?(:Overridden).should == @non_existent
+
+    path = fixture(__FILE__, "autoload_overridden.rb")
+    ModuleSpecs::Autoload.autoload :Overridden, path
+    ModuleSpecs::Autoload.autoload?(:Overridden).should == path
+
+    ModuleSpecs::Autoload::Overridden.should == :overridden
+  end
+
   it "loads the registered constant when it is accessed" do
     ModuleSpecs::Autoload.should_not have_constant(:X)
     ModuleSpecs::Autoload.autoload :X, fixture(__FILE__, "autoload_x.rb")
+    @remove << :X
     ModuleSpecs::Autoload::X.should == :x
-    ModuleSpecs::Autoload.send(:remove_const, :X)
   end
 
   it "loads the registered constant into a dynamically created class" do
     cls = Class.new { autoload :C, fixture(__FILE__, "autoload_c.rb") }
     ModuleSpecs::Autoload::DynClass = cls
+    @remove << :DynClass
 
     ScratchPad.recorded.should be_nil
     ModuleSpecs::Autoload::DynClass::C.new.loaded.should == :dynclass_c
@@ -58,6 +82,7 @@ describe "Module#autoload" do
   it "loads the registered constant into a dynamically created module" do
     mod = Module.new { autoload :D, fixture(__FILE__, "autoload_d.rb") }
     ModuleSpecs::Autoload::DynModule = mod
+    @remove << :DynModule
 
     ScratchPad.recorded.should be_nil
     ModuleSpecs::Autoload::DynModule::D.new.loaded.should == :dynmodule_d
@@ -95,6 +120,7 @@ describe "Module#autoload" do
 
   it "does not load the file when the constant is already set" do
     ModuleSpecs::Autoload.autoload :I, fixture(__FILE__, "autoload_i.rb")
+    @remove << :I
     ModuleSpecs::Autoload.const_set :I, 3
     ModuleSpecs::Autoload::I.should == 3
     ScratchPad.recorded.should be_nil
@@ -116,6 +142,7 @@ describe "Module#autoload" do
   it "does not load the file if the file is manually required" do
     filename = fixture(__FILE__, "autoload_k.rb")
     ModuleSpecs::Autoload.autoload :KHash, filename
+    @remove << :KHash
 
     require filename
     ScratchPad.recorded.should == :loaded
@@ -135,8 +162,8 @@ describe "Module#autoload" do
     ScratchPad.clear
 
     ModuleSpecs::Autoload.autoload :S, filename
+    @remove << :S
     ModuleSpecs::Autoload.autoload?(:S).should be_nil
-    ModuleSpecs::Autoload.send(:remove_const, :S)
   end
 
   it "retains the autoload even if the request to require fails" do
@@ -182,11 +209,10 @@ describe "Module#autoload" do
       module ModuleSpecs::Autoload
         autoload :GoodParent, fixture(__FILE__, "autoload_nested.rb")
       end
+      @remove << :GoodParent
 
       defined?(ModuleSpecs::Autoload::GoodParent::Nested).should == 'constant'
       ScratchPad.recorded.should == :loaded
-
-      ModuleSpecs::Autoload.send(:remove_const, :GoodParent)
     end
 
     it "returns nil when it fails to load an autoloaded parent when referencing a nested constant" do
@@ -199,11 +225,12 @@ describe "Module#autoload" do
     end
   end
 
-  describe "the autoload is removed when the same file is required directly without autoload" do
+  describe "the autoload is triggered when the same file is required directly" do
     before :each do
       module ModuleSpecs::Autoload
         autoload :RequiredDirectly, fixture(__FILE__, "autoload_required_directly.rb")
       end
+      @remove << :RequiredDirectly
       @path = fixture(__FILE__, "autoload_required_directly.rb")
       @check = -> {
         [
@@ -214,10 +241,6 @@ describe "Module#autoload" do
       ScratchPad.record @check
     end
 
-    after :each do
-      ModuleSpecs::Autoload.send(:remove_const, :RequiredDirectly)
-    end
-
     it "with a full path" do
       @check.call.should == ["constant", @path]
       require @path
@@ -242,7 +265,7 @@ describe "Module#autoload" do
       nested_require = -> {
         result = nil
         ScratchPad.record -> {
-          result = [@check.call, Thread.new { @check.call }.value]
+          result = @check.call
         }
         require nested
         result
@@ -251,24 +274,41 @@ describe "Module#autoload" do
 
       @check.call.should == ["constant", @path]
       require @path
-      cur, other = ScratchPad.recorded
-      cur.should == [nil, nil]
-      other.should == [nil, nil]
+      ScratchPad.recorded.should == [nil, nil]
       @check.call.should == ["constant", nil]
     end
   end
 
+  describe "after the autoload is triggered by require" do
+    before :each do
+      @path = tmp("autoload.rb")
+    end
+
+    after :each do
+      rm_r @path
+    end
+
+    it "the mapping feature to autoload is removed, and a new autoload with the same path is considered" do
+      ModuleSpecs::Autoload.autoload :RequireMapping1, @path
+      touch(@path) { |f| f.puts "ModuleSpecs::Autoload::RequireMapping1 = 1" }
+      ModuleSpecs::Autoload::RequireMapping1.should == 1
+
+      $LOADED_FEATURES.delete(@path)
+      ModuleSpecs::Autoload.autoload :RequireMapping2, @path[0...-3]
+      @remove << :RequireMapping2
+      touch(@path) { |f| f.puts "ModuleSpecs::Autoload::RequireMapping2 = 2" }
+      ModuleSpecs::Autoload::RequireMapping2.should == 2
+    end
+  end
+
   describe "during the autoload before the constant is assigned" do
     before :each do
       @path = fixture(__FILE__, "autoload_during_autoload.rb")
       ModuleSpecs::Autoload.autoload :DuringAutoload, @path
+      @remove << :DuringAutoload
       raise unless ModuleSpecs::Autoload.autoload?(:DuringAutoload) == @path
     end
 
-    after :each do
-      ModuleSpecs::Autoload.send(:remove_const, :DuringAutoload)
-    end
-
     def check_before_during_thread_after(&check)
       before = check.call
       to_autoload_thread, from_autoload_thread = Queue.new, Queue.new
@@ -419,6 +459,7 @@ describe "Module#autoload" do
         X = get_value
       end
     end
+    @remove << :U
 
     ModuleSpecs::Autoload::U::V::X.should == :autoload_uvx
   end
@@ -474,6 +515,7 @@ describe "Module#autoload" do
     end
 
     it "and fails when finding the undefined autoload constant in the the current scope when declared in current and defined in parent" do
+      @remove << :DeclaredInCurrentDefinedInParent
       module ModuleSpecs::Autoload
         ScratchPad.record -> {
           DeclaredInCurrentDefinedInParent = :declared_in_current_defined_in_parent
@@ -494,6 +536,7 @@ describe "Module#autoload" do
     end
 
     it "in the included modules" do
+      @remove << :DefinedInIncludedModule
       module ModuleSpecs::Autoload
         ScratchPad.record -> {
           module DefinedInIncludedModule
@@ -507,6 +550,7 @@ describe "Module#autoload" do
     end
 
     it "in the included modules of the superclass" do
+      @remove << :DefinedInSuperclassIncludedModule
       module ModuleSpecs::Autoload
         class LookupAfterAutoloadSuper
         end
@@ -528,6 +572,7 @@ describe "Module#autoload" do
     end
 
     it "in the prepended modules" do
+      @remove << :DefinedInPrependedModule
       module ModuleSpecs::Autoload
         ScratchPad.record -> {
           module DefinedInPrependedModule
@@ -567,10 +612,10 @@ describe "Module#autoload" do
         end
       end
     end
+    @remove << :W
 
     ModuleSpecs::Autoload::W::Y.should be_kind_of(Class)
     ScratchPad.recorded.should == :loaded
-    ModuleSpecs::Autoload::W.send(:remove_const, :Y)
   end
 
   it "does not call #require a second time and does not warn if already loading the same feature with #require" do
@@ -611,6 +656,7 @@ describe "Module#autoload" do
 
   it "shares the autoload request across dup'ed copies of modules" do
     require fixture(__FILE__, "autoload_s.rb")
+    @remove << :S
     filename = fixture(__FILE__, "autoload_t.rb")
     mod1 = Module.new { autoload :T, filename }
     lambda {
@@ -651,8 +697,9 @@ describe "Module#autoload" do
 
   describe "on a frozen module" do
     it "raises a #{frozen_error_class} before setting the name" do
-      lambda { @frozen_module.autoload :Foo, @non_existent }.should raise_error(frozen_error_class)
-      @frozen_module.should_not have_constant(:Foo)
+      frozen_module = Module.new.freeze
+      lambda { frozen_module.autoload :Foo, @non_existent }.should raise_error(frozen_error_class)
+      frozen_module.should_not have_constant(:Foo)
     end
   end
 
@@ -675,6 +722,7 @@ describe "Module#autoload" do
   describe "(concurrently)" do
     it "blocks a second thread while a first is doing the autoload" do
       ModuleSpecs::Autoload.autoload :Concur, fixture(__FILE__, "autoload_concur.rb")
+      @remove << :Concur
 
       start = false
 
@@ -717,8 +765,6 @@ describe "Module#autoload" do
       t2_val.should == t1_val
 
       t2_exc.should be_nil
-
-      ModuleSpecs::Autoload.send(:remove_const, :Concur)
     end
 
     # https://bugs.ruby-lang.org/issues/10892
diff --git a/spec/ruby/core/module/const_set_spec.rb b/spec/ruby/core/module/const_set_spec.rb
index f3c69cd3e0..25d22ffaba 100644
--- a/spec/ruby/core/module/const_set_spec.rb
+++ b/spec/ruby/core/module/const_set_spec.rb
@@ -72,6 +72,53 @@ describe "Module#const_set" do
     lambda { ConstantSpecs.const_set name, 1 }.should raise_error(TypeError)
   end
 
+  describe "when overwriting an existing constant" do
+    it "warns if the previous value was a normal value" do
+      mod = Module.new
+      mod.const_set :Foo, 42
+      -> {
+        mod.const_set :Foo, 1
+      }.should complain(/already initialized constant/)
+      mod.const_get(:Foo).should == 1
+    end
+
+    it "does not warn if the previous value was an autoload" do
+      mod = Module.new
+      mod.autoload :Foo, "not-existing"
+      -> {
+        mod.const_set :Foo, 1
+      }.should_not complain
+      mod.const_get(:Foo).should == 1
+    end
+
+    it "does not warn if the previous value was undefined" do
+      path = fixture(__FILE__, "autoload_o.rb")
+      ScratchPad.record []
+      mod = Module.new
+
+      mod.autoload :Foo, path
+      -> { mod::Foo }.should raise_error(NameError)
+
+      mod.should have_constant(:Foo)
+      mod.const_defined?(:Foo).should == false
+      mod.autoload?(:Foo).should == nil
+
+      -> {
+        mod.const_set :Foo, 1
+      }.should_not complain
+      mod.const_get(:Foo).should == 1
+    end
+
+    it "does not warn if the new value is an autoload" do
+      mod = Module.new
+      mod.const_set :Foo, 42
+      -> {
+        mod.autoload :Foo, "not-existing"
+      }.should_not complain
+      mod.const_get(:Foo).should == 42
+    end
+  end
+
   describe "on a frozen module" do
     before :each do
       @frozen = Module.new.freeze
diff --git a/spec/ruby/core/module/fixtures/autoload_overridden.rb b/spec/ruby/core/module/fixtures/autoload_overridden.rb
new file mode 100644
index 0000000000..7062bcfabc
--- /dev/null
+++ b/spec/ruby/core/module/fixtures/autoload_overridden.rb
@@ -0,0 +1,3 @@
+module ModuleSpecs::Autoload
+  Overridden = :overridden
+end
diff --git a/spec/ruby/core/string/end_with_spec.rb b/spec/ruby/core/string/end_with_spec.rb
index 7268378a38..429888803c 100644
--- a/spec/ruby/core/string/end_with_spec.rb
+++ b/spec/ruby/core/string/end_with_spec.rb
@@ -47,4 +47,11 @@ describe "String#end_with?" do
     "céréale".end_with?("réale").should be_true
   end
 
+  it "raises an Encoding::CompatibilityError if the encodings are incompatible" do
+    pat = "ア".encode Encoding::EUC_JP
+    lambda do
+      "あれ".end_with?(pat)
+    end.should raise_error(Encoding::CompatibilityError)
+  end
+
 end
diff --git a/spec/ruby/core/string/inspect_spec.rb b/spec/ruby/core/string/inspect_spec.rb
index 2cfcfe0e76..c1674c73c8 100644
--- a/spec/ruby/core/string/inspect_spec.rb
+++ b/spec/ruby/core/string/inspect_spec.rb
@@ -489,4 +489,12 @@ describe "String#inspect" do
       ].should be_computed_by(:inspect)
     end
   end
+
+  describe "when the string's encoding is different than the result's encoding" do
+    describe "and the string's encoding is ASCII-compatible but the characters are non-ASCII" do
+      it "returns a string with the non-ASCII characters replaced by \\x notation" do
+        "\u{3042}".encode("EUC-JP").inspect.should == '"\\x{A4A2}"'
+      end
+    end
+  end
 end
diff --git a/spec/ruby/core/thread/list_spec.rb b/spec/ruby/core/thread/list_spec.rb
index bd56cb4c52..80dd15c6ca 100644
--- a/spec/ruby/core/thread/list_spec.rb
+++ b/spec/ruby/core/thread/list_spec.rb
@@ -35,8 +35,21 @@ describe "Thread.list" do
       t.join
     end
   end
-end
 
-describe "Thread.list" do
-  it "needs to be reviewed for spec completeness"
+  it "returns instances of Thread and not null or nil values" do
+    spawner = Thread.new do
+      Array.new(100) do
+        Thread.new {}
+      end
+    end
+
+    while spawner.alive?
+      Thread.list.each { |th|
+        th.should be_kind_of(Thread)
+      }
+    end
+
+    threads = spawner.value
+    threads.each(&:join)
+  end
 end
diff --git a/spec/ruby/core/tracepoint/eval_script_spec.rb b/spec/ruby/core/tracepoint/eval_script_spec.rb
index 8a153156d1..1d8e425a9a 100644
--- a/spec/ruby/core/tracepoint/eval_script_spec.rb
+++ b/spec/ruby/core/tracepoint/eval_script_spec.rb
@@ -2,21 +2,23 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 ruby_version_is "2.6" do
-  describe "#eval_script" do
-    ScratchPad.record []
+  describe "TracePoint#eval_script" do
+    it "is the evald source code" do
+      ScratchPad.record []
 
-    script = <<-CODE
-      def foo
-        p :hello
+      script = <<-CODE
+        def foo
+          p :hello
+        end
+      CODE
+
+      TracePoint.new(:script_compiled) do |e|
+        ScratchPad << e.eval_script
+      end.enable do
+        eval script
       end
-    CODE
 
-    TracePoint.new(:script_compiled) do |e|
-      ScratchPad << e.eval_script
-    end.enable do
-      eval script
+      ScratchPad.recorded.should == [script]
     end
-
-    ScratchPad.recorded.should == [script]
   end
 end
diff --git a/spec/ruby/core/tracepoint/instruction_sequence_spec.rb b/spec/ruby/core/tracepoint/instruction_sequence_spec.rb
index 50a9cd5722..3e3b73cccc 100644
--- a/spec/ruby/core/tracepoint/instruction_sequence_spec.rb
+++ b/spec/ruby/core/tracepoint/instruction_sequence_spec.rb
@@ -2,22 +2,24 @@ require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 
 ruby_version_is "2.6" do
-  describe "#instruction_sequence" do
-    ScratchPad.record []
+  describe "TracePoint#instruction_sequence" do
+    it "is an instruction sequence" do
+      ScratchPad.record []
 
-    script = <<-CODE
-      def foo
-        p :hello
+      script = <<-CODE
+        def foo
+          p :hello
+        end
+      CODE
+
+      TracePoint.new(:script_compiled) do |e|
+        ScratchPad << e.instruction_sequence
+      end.enable do
+        eval script
       end
-    CODE
 
-    TracePoint.new(:script_compiled) do |e|
-      ScratchPad << e.instruction_sequence
-    end.enable do
-      eval script
+      ScratchPad.recorded.size.should == 1
+      ScratchPad.recorded[0].class.should == RubyVM::InstructionSequence
     end
-
-    ScratchPad.recorded.size.should == 1
-    ScratchPad.recorded[0].class.should == RubyVM::InstructionSequence
   end
 end
diff --git a/spec/ruby/language/alias_spec.rb b/spec/ruby/language/alias_spec.rb
index 306c2776b4..a7f34146d1 100644
--- a/spec/ruby/language/alias_spec.rb
+++ b/spec/ruby/language/alias_spec.rb
@@ -244,3 +244,15 @@ describe "The alias keyword" do
     }
   end
 end
+
+describe "The alias keyword" do
+  it "can create a new global variable, synonym of the original" do
+    code = '$a = 1; alias $b $a; p [$a, $b]; $b = 2; p [$a, $b]'
+    ruby_exe(code).should == "[1, 1]\n[2, 2]\n"
+  end
+
+  it "can override an existing global variable and make them synonyms" do
+    code = '$a = 1; $b = 2; alias $b $a; p [$a, $b]; $b = 3; p [$a, $b]'
+    ruby_exe(code).should == "[1, 1]\n[3, 3]\n"
+  end
+end
diff --git a/spec/ruby/language/fixtures/for_scope.rb b/spec/ruby/language/fixtures/for_scope.rb
new file mode 100644
index 0000000000..9c44a23a2c
--- /dev/null
+++ b/spec/ruby/language/fixtures/for_scope.rb
@@ -0,0 +1,15 @@
+module ForSpecs
+  class ForInClassMethod
+    m = :same_variable_set_outside
+
+    def self.foo
+      all = []
+      for m in [:bar, :baz]
+        all << m
+      end
+      all
+    end
+
+    READER = -> { m }
+  end
+end
diff --git a/spec/ruby/language/for_spec.rb b/spec/ruby/language/for_spec.rb
index 7d725430c6..0ad5ea88af 100644
--- a/spec/ruby/language/for_spec.rb
+++ b/spec/ruby/language/for_spec.rb
@@ -1,4 +1,5 @@
 require_relative '../spec_helper'
+require_relative 'fixtures/for_scope'
 
 # for name[, name]... in expr [do]
 #   body
@@ -130,6 +131,11 @@ describe "The for expression" do
     a.should == 123
   end
 
+  it "does not try to access variables outside the method" do
+    ForSpecs::ForInClassMethod.foo.should == [:bar, :baz]
+    ForSpecs::ForInClassMethod::READER.call.should == :same_variable_set_outside
+  end
+
   it "returns expr" do
     for i in 1..3; end.should == (1..3)
     for i,j in { 1 => 10, 2 => 20 }; end.should == { 1 => 10, 2 => 20 }
diff --git a/spec/ruby/language/method_spec.rb b/spec/ruby/language/method_spec.rb
index 49837fa638..b0fc521d69 100644
--- a/spec/ruby/language/method_spec.rb
+++ b/spec/ruby/language/method_spec.rb
@@ -574,6 +574,7 @@ describe "A method" do
       m(a: 1, b: 2).should == { a: 1, b: 2 }
       m(*[]).should == {}
       m(**{}).should == {}
+      m(**{a: 1, b: 2}, **{a: 4, c: 7}).should == { a: 4, b: 2, c: 7 }
       lambda { m(2) }.should raise_error(ArgumentError)
     end
 
diff --git a/spec/ruby/library/bigdecimal/add_spec.rb b/spec/ruby/library/bigdecimal/add_spec.rb
index 024dd576cc..1ae5b7f428 100644
--- a/spec/ruby/library/bigdecimal/add_spec.rb
+++ b/spec/ruby/library/bigdecimal/add_spec.rb
@@ -73,6 +73,14 @@ describe "BigDecimal#add" do
 #    BigDecimal("0.88").add(0.0, 1).should == BigDecimal("0.9")
 #  end
 
+  describe "with Object" do
+    it "tries to coerce the other operand to self" do
+      object = mock("Object")
+      object.should_receive(:coerce).with(@frac_3).and_return([@frac_3, @frac_4])
+      @frac_3.add(object, 1).should == BigDecimal("0.1E16")
+    end
+  end
+
   it "favors the precision specified in the second argument over the global limit" do
     BigDecimalSpecs.with_limit(1) do
       BigDecimal('0.888').add(@zero, 3).should == BigDecimal('0.888')
diff --git a/spec/ruby/library/bigdecimal/div_spec.rb b/spec/ruby/library/bigdecimal/div_spec.rb
index a774376f55..23d1ae1efd 100644
--- a/spec/ruby/library/bigdecimal/div_spec.rb
+++ b/spec/ruby/library/bigdecimal/div_spec.rb
@@ -42,6 +42,14 @@ describe "BigDecimal#div" do
     }
   end
 
+  describe "with Object" do
+    it "tries to coerce the other operand to self" do
+      object = mock("Object")
+      object.should_receive(:coerce).with(@one).and_return([@one, @two])
+      @one.div(object).should == @zero
+    end
+  end
+
   it "raises FloatDomainError if NaN is involved" do
     lambda { @one.div(@nan) }.should raise_error(FloatDomainError)
     lambda { @nan.div(@one) }.should raise_error(FloatDomainError)
diff --git a/spec/ruby/library/bigdecimal/mult_spec.rb b/spec/ruby/library/bigdecimal/mult_spec.rb
index a4c1602182..b7f8044b0b 100644
--- a/spec/ruby/library/bigdecimal/mult_spec.rb
+++ b/spec/ruby/library/bigdecimal/mult_spec.rb
@@ -9,7 +9,8 @@ end
 describe "BigDecimal#mult" do
   before :each do
     @one = BigDecimal "1"
-    @e3_minus = BigDecimal "3E-20001"
+    @e3_minus = BigDecimal("3E-20001")
+    @e3_plus = BigDecimal("3E20001")
     @e = BigDecimal "1.00000000000000000000123456789"
     @tolerance = @e.sub @one, 1000
     @tolerance2 = BigDecimal "30001E-20005"
@@ -21,4 +22,11 @@ describe "BigDecimal#mult" do
     @e3_minus.mult(@one, 1).should be_close(0, @tolerance2)
   end
 
+  describe "with Object" do
+    it "tries to coerce the other operand to self" do
+      object = mock("Object")
+      object.should_receive(:coerce).with(@e3_minus).and_return([@e3_minus, @e3_plus])
+      @e3_minus.mult(object, 1).should == BigDecimal("9")
+    end
+  end
 end
diff --git a/spec/ruby/library/bigdecimal/multiply_spec.rb b/spec/ruby/library/bigdecimal/multiply_spec.rb
index 2741d3623e..4e5a8d6681 100644
--- a/spec/ruby/library/bigdecimal/multiply_spec.rb
+++ b/spec/ruby/library/bigdecimal/multiply_spec.rb
@@ -23,4 +23,12 @@ describe "BigDecimal#*" do
     (@e3_minus * @e3_minus).should == BigDecimal("9E-40002")
     (@e * @one).should == @e
   end
+
+  describe "with Object" do
+    it "tries to coerce the other operand to self" do
+      object = mock("Object")
+      object.should_receive(:coerce).with(@e3_minus).and_return([@e3_minus, @e3_plus])
+      (@e3_minus * object).should == BigDecimal("9")
+    end
+  end
 end
diff --git a/spec/ruby/library/bigdecimal/remainder_spec.rb b/spec/ruby/library/bigdecimal/remainder_spec.rb
index 28b25f8566..8626064a2f 100644
--- a/spec/ruby/library/bigdecimal/remainder_spec.rb
+++ b/spec/ruby/library/bigdecimal/remainder_spec.rb
@@ -5,7 +5,8 @@ describe "BigDecimal#remainder" do
 
   before :each do
     @zero = BigDecimal("0")
-    @one = BigDecimal("0")
+    @one = BigDecimal("1")
+    @three = BigDecimal("3")
     @mixed = BigDecimal("1.23456789")
     @pos_int = BigDecimal("2E5555")
     @neg_int = BigDecimal("-2E5555")
@@ -71,9 +72,16 @@ describe "BigDecimal#remainder" do
   end
 
   it "coerces arguments to BigDecimal if possible" do
-    @one.remainder(2).should == @one
+    @three.remainder(2).should == @one
   end
 
+  describe "with Object" do
+    it "tries to coerce the other operand to self" do
+      object = mock("Object")
+      object.should_receive(:coerce).with(@three).and_return([@three, 2])
+      @three.remainder(object).should == @one
+    end
+  end
 
   it "raises TypeError if the argument cannot be coerced to BigDecimal" do
     lambda {
diff --git a/spec/ruby/library/bigdecimal/shared/modulo.rb b/spec/ruby/library/bigdecimal/shared/modulo.rb
index c9691cbf37..d570b86d7a 100644
--- a/spec/ruby/library/bigdecimal/shared/modulo.rb
+++ b/spec/ruby/library/bigdecimal/shared/modulo.rb
@@ -70,6 +70,15 @@ describe :bigdecimal_modulo, shared: true do
     res.kind_of?(BigDecimal).should == true
   end
 
+  describe "with Object" do
+    it "tries to coerce the other operand to self" do
+      bd6543 = BigDecimal("6543.21")
+      object = mock("Object")
+      object.should_receive(:coerce).with(bd6543).and_return([bd6543, 137])
+      bd6543.send(@method, object, *@object).should == BigDecimal("104.21")
+    end
+  end
+
   it "returns NaN if NaN is involved" do
     @nan.send(@method, @nan).nan?.should == true
     @nan.send(@method, @one).nan?.should == true
diff --git a/spec/ruby/library/bigdecimal/shared/quo.rb b/spec/ruby/library/bigdecimal/shared/quo.rb
index cb51c10d71..4d6d64b787 100644
--- a/spec/ruby/library/bigdecimal/shared/quo.rb
+++ b/spec/ruby/library/bigdecimal/shared/quo.rb
@@ -29,6 +29,14 @@ describe :bigdecimal_quo, shared: true do
     @one.send(@method, BigDecimal('2E-5555'), *@object).should == BigDecimal('0.5E5555')
   end
 
+  describe "with Object" do
+    it "tries to coerce the other operand to self" do
+      object = mock("Object")
+      object.should_receive(:coerce).with(@one).and_return([@one, @two])
+      @one.send(@method, object, *@object).should == BigDecimal("0.5")
+    end
+  end
+
   it "returns 0 if divided by Infinity" do
     @zero.send(@method, @infinity, *@object).should == 0
     @frac_2.send(@method, @infinity, *@object).should == 0
diff --git a/spec/ruby/library/bigdecimal/sub_spec.rb b/spec/ruby/library/bigdecimal/sub_spec.rb
index 7f0305a1c6..f0068b12a9 100644
--- a/spec/ruby/library/bigdecimal/sub_spec.rb
+++ b/spec/ruby/library/bigdecimal/sub_spec.rb
@@ -13,6 +13,8 @@ describe "BigDecimal#sub" do
     @one_minus = BigDecimal("-1")
     @frac_1 = BigDecimal("1E-99999")
     @frac_2 = BigDecimal("0.9E-99999")
+    @frac_3 = BigDecimal("12345E10")
+    @frac_4 = BigDecimal("98765E10")
   end
 
   it "returns a - b with given precision" do
@@ -32,6 +34,14 @@ describe "BigDecimal#sub" do
     @frac_1.sub(@frac_1, 1000000).should == @zero
   end
 
+  describe "with Object" do
+    it "tries to coerce the other operand to self" do
+      object = mock("Object")
+      object.should_receive(:coerce).with(@frac_3).and_return([@frac_3, @frac_4])
+      @frac_3.sub(object, 1).should == BigDecimal("-0.9E15")
+    end
+  end
+
   it "returns NaN if NaN is involved" do
     @one.sub(@nan, 1).nan?.should == true
     @nan.sub(@one, 1).nan?.should == true
diff --git a/spec/ruby/library/bigdecimal/util_spec.rb b/spec/ruby/library/bigdecimal/util_spec.rb
new file mode 100644
index 0000000000..f41e131144
--- /dev/null
+++ b/spec/ruby/library/bigdecimal/util_spec.rb
@@ -0,0 +1,42 @@
+require_relative '../../spec_helper'
+require 'bigdecimal'
+require 'bigdecimal/util'
+
+describe "BigDecimal's util method definitions" do
+  describe "#to_d" do
+    it "should define #to_d on Integer" do
+      42.to_d.should == BigDecimal(42)
+    end
+
+    it "should define #to_d on Float" do
+      0.5.to_d.should == BigDecimal(0.5, Float::DIG)
+      1.234.to_d(2).should == BigDecimal(1.234, 2)
+    end
+
+    it "should define #to_d on String" do
+      "0.5".to_d.should == BigDecimal(0.5, Float::DIG)
+      "45.67 degrees".to_d.should == BigDecimal(45.67, Float::DIG)
+    end
+
+    it "should define #to_d on BigDecimal" do
+      bd = BigDecimal("3.14")
+      bd.to_d.should equal(bd)
+    end
+
+    it "should define #to_d on Rational" do
+      Rational(22, 7).to_d(3).should == BigDecimal(3.14, 3)
+    end
+
+    ruby_version_is "2.6" do
+      it "should define #to_d on nil" do
+        nil.to_d.should == BigDecimal(0)
+      end
+    end
+  end
+
+  describe "#to_digits" do
+    it "should define #to_digits on BigDecimal" do
+      BigDecimal("3.14").to_digits.should == "3.14"
+    end
+  end
+end
diff --git a/spec/ruby/library/rbconfig/rbconfig_spec.rb b/spec/ruby/library/rbconfig/rbconfig_spec.rb
index 8fa63b6e27..71e3d376d1 100644
--- a/spec/ruby/library/rbconfig/rbconfig_spec.rb
+++ b/spec/ruby/library/rbconfig/rbconfig_spec.rb
@@ -10,7 +10,7 @@ describe 'RbConfig::CONFIG' do
   end
 
   # These directories have no meanings before the installation.
-  if RbConfig::TOPDIR
+  guard -> { RbConfig::TOPDIR } do
     it "['rubylibdir'] returns the directory containing Ruby standard libraries" do
       rubylibdir = RbConfig::CONFIG['rubylibdir']
       File.directory?(rubylibdir).should == true
diff --git a/spec/ruby/optional/capi/ext/string_spec.c b/spec/ruby/optional/capi/ext/string_spec.c
index 3eeceae743..3255c4450d 100644
--- a/spec/ruby/optional/capi/ext/string_spec.c
+++ b/spec/ruby/optional/capi/ext/string_spec.c
@@ -358,6 +358,14 @@ static VALUE string_spec_rb_sprintf2(VALUE self, VALUE str, VALUE repl1, VALUE r
   return rb_sprintf(RSTRING_PTR(str), RSTRING_PTR(repl1), RSTRING_PTR(repl2));
 }
 
+static VALUE string_spec_rb_sprintf3(VALUE self, VALUE str) {
+  return rb_sprintf("Result: %"PRIsVALUE".", str);
+}
+  
+static VALUE string_spec_rb_sprintf4(VALUE self, VALUE str) {
+  return rb_sprintf("Result: %+"PRIsVALUE".", str);
+}
+  
 static VALUE string_spec_rb_vsprintf_worker(char* fmt, ...) {
   va_list varargs;
   VALUE str;
@@ -463,6 +471,8 @@ void Init_string_spec(void) {
   rb_define_method(cls, "rb_str_free", string_spec_rb_str_free, 1);
   rb_define_method(cls, "rb_sprintf1", string_spec_rb_sprintf1, 2);
   rb_define_method(cls, "rb_sprintf2", string_spec_rb_sprintf2, 3);
+  rb_define_method(cls, "rb_sprintf3", string_spec_rb_sprintf3, 1);
+  rb_define_method(cls, "rb_sprintf4", string_spec_rb_sprintf4, 1);
   rb_define_method(cls, "rb_vsprintf", string_spec_rb_vsprintf, 4);
   rb_define_method(cls, "rb_str_equal", string_spec_rb_str_equal, 2);
   rb_define_method(cls, "rb_usascii_str_new", string_spec_rb_usascii_str_new, 2);
diff --git a/spec/ruby/optional/capi/ext/typed_data_spec.c b/spec/ruby/optional/capi/ext/typed_data_spec.c
index 60408a5750..a2cc53f54d 100644
--- a/spec/ruby/optional/capi/ext/typed_data_spec.c
+++ b/spec/ruby/optional/capi/ext/typed_data_spec.c
@@ -43,7 +43,11 @@ void sample_typed_wrapped_struct_mark(void* st) {
 }
 
 size_t sample_typed_wrapped_struct_memsize(const void* st) {
-  return sizeof(struct sample_typed_wrapped_struct);
+  if (st == NULL) {
+    return 0;
+  } else {
+    return ((struct sample_typed_wrapped_struct *)st)->foo;
+  }
 }
 
 static const rb_data_type_t sample_typed_wrapped_struct_data_type = {
diff --git a/spec/ruby/optional/capi/kernel_spec.rb b/spec/ruby/optional/capi/kernel_spec.rb
index 627442104f..f68a46ed50 100644
--- a/spec/ruby/optional/capi/kernel_spec.rb
+++ b/spec/ruby/optional/capi/kernel_spec.rb
@@ -244,6 +244,10 @@ describe "C-API Kernel function" do
       @s.rb_yield_splat([1, 2]) { |x, y| x + y }.should == 3
     end
 
+    it "passes arguments to a block accepting splatted args" do
+      @s.rb_yield_splat([1, 2]) { |*v| v }.should == [1, 2]
+    end
+
     it "raises LocalJumpError when no block is given" do
       lambda { @s.rb_yield_splat([1, 2]) }.should raise_error(LocalJumpError)
     end
diff --git a/spec/ruby/optional/capi/mutex_spec.rb b/spec/ruby/optional/capi/mutex_spec.rb
index 8844d311f2..1b76c5c250 100644
--- a/spec/ruby/optional/capi/mutex_spec.rb
+++ b/spec/ruby/optional/capi/mutex_spec.rb
@@ -72,9 +72,10 @@ describe "C-API Mutex functions" do
 
     it "sleeps when the mutex is locked" do
       @m.lock
-      start = Time.now
-      @s.rb_mutex_sleep(@m, 0.1)
-      (Time.now - start).should be_close(0.1, 0.2)
+      t1 = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+      @s.rb_mutex_sleep(@m, 0.001)
+      t2 = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+      (t2 - t1).should >= 0
       @m.locked?.should be_true
     end
   end
diff --git a/spec/ruby/optional/capi/string_spec.rb b/spec/ruby/optional/capi/string_spec.rb
index 5ad8169e8e..ac23198662 100644
--- a/spec/ruby/optional/capi/string_spec.rb
+++ b/spec/ruby/optional/capi/string_spec.rb
@@ -4,6 +4,30 @@ require_relative '../../shared/string/times'
 
 load_extension('string')
 
+class CApiStringSpecs
+  class ValidTostrTest
+    def to_str
+      "ruby"
+    end
+  end
+
+  class InvalidTostrTest
+    def to_str
+      []
+    end
+  end
+
+  class ToSOrInspect
+    def to_s
+      'A string'
+    end
+
+    def inspect
+      'A different string'
+    end
+  end
+end
+
 describe :rb_str_new2, shared: true do
   it "returns a new string object calling strlen on the passed C string" do
     # Hardcoded to pass const char * = "hello\0invisible"
@@ -20,18 +44,6 @@ describe "C-API String function" do
     @s = CApiStringSpecs.new
   end
 
-  class ValidTostrTest
-    def to_str
-      "ruby"
-    end
-  end
-
-  class InvalidTostrTest
-    def to_str
-      []
-    end
-  end
-
   [Encoding::BINARY, Encoding::UTF_8].each do |enc|
     describe "rb_str_set_len on a #{enc.name} String" do
       before :each do
@@ -438,12 +450,12 @@ describe "C-API String function" do
   describe "rb_str_to_str" do
     it "calls #to_str to coerce the value to a String" do
       @s.rb_str_to_str("foo").should == "foo"
-      @s.rb_str_to_str(ValidTostrTest.new).should == "ruby"
+      @s.rb_str_to_str(CApiStringSpecs::ValidTostrTest.new).should == "ruby"
     end
 
     it "raises a TypeError if coercion fails" do
       lambda { @s.rb_str_to_str(0) }.should raise_error(TypeError)
-      lambda { @s.rb_str_to_str(InvalidTostrTest.new) }.should raise_error(TypeError)
+      lambda { @s.rb_str_to_str(CApiStringSpecs::InvalidTostrTest.new) }.should raise_error(TypeError)
     end
   end
 
@@ -875,6 +887,26 @@ describe "C-API String function" do
       s = "Awesome %s is here with %s"
       @s.rb_sprintf2(s, "string", "content").should == "Awesome string is here with content"
     end
+
+    it "formats a string VALUE using to_s if sign not specified in format" do
+      s = 'Result: A string.'
+      @s.rb_sprintf3(CApiStringSpecs::ToSOrInspect.new).should == s
+    end
+
+    it "formats a string VALUE using inspect if sign specified in format" do
+      s = 'Result: A different string.'
+      @s.rb_sprintf4(CApiStringSpecs::ToSOrInspect.new).should == s
+    end
+
+    it "formats a TrueClass VALUE as `TrueClass` if sign not specified in format" do
+      s = 'Result: TrueClass.'
+      @s.rb_sprintf3(true.class).should == s
+    end
+
+    it "formats a TrueClass VALUE as 'true' if sign specified in format" do
+      s = 'Result: true.'
+      @s.rb_sprintf4(true.class).should == s
+    end
   end
 
   describe "rb_vsprintf" do
@@ -890,11 +922,11 @@ describe "C-API String function" do
     end
 
     it "tries to convert the passed argument to a string by calling #to_str first" do
-      @s.rb_String(ValidTostrTest.new).should == "ruby"
+      @s.rb_String(CApiStringSpecs::ValidTostrTest.new).should == "ruby"
     end
 
     it "raises a TypeError if #to_str does not return a string" do
-      lambda { @s.rb_String(InvalidTostrTest.new) }.should raise_error(TypeError)
+      lambda { @s.rb_String(CApiStringSpecs::InvalidTostrTest.new) }.should raise_error(TypeError)
     end
 
     it "tries to convert the passed argument to a string by calling #to_s" do
diff --git a/spec/ruby/optional/capi/typed_data_spec.rb b/spec/ruby/optional/capi/typed_data_spec.rb
index b0c0cd48ed..8d2910457c 100644
--- a/spec/ruby/optional/capi/typed_data_spec.rb
+++ b/spec/ruby/optional/capi/typed_data_spec.rb
@@ -1,4 +1,5 @@
 require_relative 'spec_helper'
+require 'objspace'
 
 load_extension("typed_data")
 
@@ -7,6 +8,14 @@ describe "CApiAllocTypedSpecs (a class with an alloc func defined)" do
     @s = CApiAllocTypedSpecs.new
     @s.typed_wrapped_data.should == 42 # not defined in initialize
   end
+
+  it "uses the specified memsize function for ObjectSpace.memsize" do
+    @s = CApiAllocTypedSpecs.new
+    # The defined memsize function for the type should return 42 as
+    # the size, and this should be added to the size of the object as
+    # known by Ruby.
+    ObjectSpace.memsize_of(@s).should > 42
+  end
 end
 
 describe "CApiWrappedTypedStruct" do
diff --git a/spec/ruby/optional/capi/util_spec.rb b/spec/ruby/optional/capi/util_spec.rb
index da2f758bec..b3e43d29ce 100644
--- a/spec/ruby/optional/capi/util_spec.rb
+++ b/spec/ruby/optional/capi/util_spec.rb
@@ -23,6 +23,10 @@ describe "C-API Util function" do
       lambda { @o.rb_scan_args([1, 2], "3", 0, @acc) }.should raise_error(ArgumentError)
     end
 
+    it "raises an ArgumentError if there are too many arguments" do
+      lambda { @o.rb_scan_args([1, 2, 3, 4], "3", 0, @acc) }.should raise_error(ArgumentError)
+    end
+
     it "assigns the required and optional arguments scanned" do
       @o.rb_scan_args([1, 2], "11", 2, @acc).should == 2
       ScratchPad.recorded.should == [1, 2]
diff --git a/spec/ruby/security/cve_2019_8321_spec.rb b/spec/ruby/security/cve_2019_8321_spec.rb
new file mode 100644
index 0000000000..affcd00e02
--- /dev/null
+++ b/spec/ruby/security/cve_2019_8321_spec.rb
@@ -0,0 +1,22 @@
+require_relative '../spec_helper'
+
+require 'rubygems'
+require 'rubygems/user_interaction'
+
+ruby_version_is "2.5.5" do
+  describe "CVE-2019-8321 is resisted by" do
+    it "sanitising verbose messages" do
+      ui = Class.new {
+        include Gem::UserInteraction
+      }.new
+      ui.should_receive(:say).with(".]2;nyan.")
+      verbose_before = Gem.configuration.verbose
+      begin
+        Gem.configuration.verbose = :really_verbose
+        ui.verbose("\e]2;nyan\a")
+      ensure
+        Gem.configuration.verbose = verbose_before
+      end
+    end
+  end
+end
diff --git a/spec/ruby/security/cve_2019_8322_spec.rb b/spec/ruby/security/cve_2019_8322_spec.rb
new file mode 100644
index 0000000000..04fb1a7a26
--- /dev/null
+++ b/spec/ruby/security/cve_2019_8322_spec.rb
@@ -0,0 +1,23 @@
+require_relative '../spec_helper'
+
+require 'yaml'
+require 'rubygems'
+require 'rubygems/safe_yaml'
+require 'rubygems/commands/owner_command'
+
+ruby_version_is "2.5.5" do
+  describe "CVE-2019-8322 is resisted by" do
+    it "sanitising owner names" do
+      command = Gem::Commands::OwnerCommand.new
+      def command.rubygems_api_request(*args)
+        Struct.new(:body).new("---\n- email: \"\e]2;nyan\a\"\n  handle: handle\n  id: id\n")
+      end
+      def command.with_response(response)
+        yield response
+      end
+      command.should_receive(:say).with("Owners for gem: name")
+      command.should_receive(:say).with("- .]2;nyan.")
+      command.show_owners "name"
+    end
+  end
+end
diff --git a/spec/ruby/security/cve_2019_8323_spec.rb b/spec/ruby/security/cve_2019_8323_spec.rb
new file mode 100644
index 0000000000..af0b270880
--- /dev/null
+++ b/spec/ruby/security/cve_2019_8323_spec.rb
@@ -0,0 +1,38 @@
+require_relative '../spec_helper'
+
+require 'optparse'
+
+require 'rubygems'
+require 'rubygems/gemcutter_utilities'
+
+ruby_version_is "2.5.5" do
+  describe "CVE-2019-8323 is resisted by" do
+    describe "sanitising the body" do
+      it "for success codes" do
+        cutter = Class.new {
+          include Gem::GemcutterUtilities
+        }.new
+        response = Net::HTTPSuccess.new(nil, nil, nil)
+        def response.body
+          "\e]2;nyan\a"
+        end
+        cutter.should_receive(:say).with(".]2;nyan.")
+        cutter.with_response response
+      end
+
+      it "for error codes" do
+        cutter = Class.new {
+          include Gem::GemcutterUtilities
+        }.new
+        def cutter.terminate_interaction(n)
+        end
+        response = Net::HTTPNotFound.new(nil, nil, nil)
+        def response.body
+          "\e]2;nyan\a"
+        end
+        cutter.should_receive(:say).with(".]2;nyan.")
+        cutter.with_response response
+      end
+    end
+  end
+end
diff --git a/spec/ruby/security/cve_2019_8325_spec.rb b/spec/ruby/security/cve_2019_8325_spec.rb
new file mode 100644
index 0000000000..dcdbe34210
--- /dev/null
+++ b/spec/ruby/security/cve_2019_8325_spec.rb
@@ -0,0 +1,38 @@
+require_relative '../spec_helper'
+
+require 'rubygems'
+require 'rubygems/command_manager'
+
+ruby_version_is "2.5.5" do
+  describe "CVE-2019-8325 is resisted by" do
+    describe "sanitising error message components" do
+      it "for the 'while executing' message" do
+        manager = Gem::CommandManager.new
+        def manager.process_args(args, build_args)
+          raise StandardError, "\e]2;nyan\a"
+        end
+        def manager.terminate_interaction(n)
+        end
+        manager.should_receive(:alert_error).with("While executing gem ... (StandardError)\n    .]2;nyan.")
+        manager.run nil, nil
+      end
+
+      it "for the 'invalid option' message" do
+        manager = Gem::CommandManager.new
+        def manager.terminate_interaction(n)
+        end
+        manager.should_receive(:alert_error).with("Invalid option: --.]2;nyan.. See 'gem --help'.")
+        manager.process_args ["--\e]2;nyan\a"], nil
+      end
+
+      it "for the 'loading command' message" do
+        manager = Gem::CommandManager.new
+        def manager.require(x)
+          raise 'foo'
+        end
+        manager.should_receive(:alert_error).with("Loading command: .]2;nyan. (RuntimeError)\n\tfoo")
+        manager.send :load_and_instantiate, "\e]2;nyan\a"
+      end
+    end
+  end
+end
diff --git a/spec/ruby/shared/basicobject/send.rb b/spec/ruby/shared/basicobject/send.rb
index 2b79ab4c2c..f96a3593bd 100644
--- a/spec/ruby/shared/basicobject/send.rb
+++ b/spec/ruby/shared/basicobject/send.rb
@@ -114,4 +114,15 @@ describe :basicobject_send, shared: true do
   it "has a negative arity" do
     method(@method).arity.should < 0
   end
+
+  it "invokes module methods with super correctly" do
+    m1 = Module.new { def foo(ary); ary << :m1; end; }
+    m2 = Module.new { def foo(ary = []); super(ary); ary << :m2; end; }
+    c2 = Class.new do
+      include m1
+      include m2
+    end
+
+    c2.new.send(@method, :foo, *[[]]).should == %i[m1 m2]
+  end
 end