Update to ruby/spec@cbfaf51

41 files changed, 526 insertions, 54 deletions

diff --git a/spec/ruby/core/enumerable/compact_spec.rb b/spec/ruby/core/enumerable/compact_spec.rb
new file mode 100644
index 0000000000..86e95dce08
--- /dev/null
+++ b/spec/ruby/core/enumerable/compact_spec.rb
@@ -0,0 +1,11 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+ruby_version_is '3.1' do
+  describe "Enumerable#compact" do
+    it 'returns array without nil elements' do
+      arr = EnumerableSpecs::Numerous.new(nil, 1, 2, nil, true)
+      arr.compact.should == [1, 2, true]
+    end
+  end
+end
diff --git a/spec/ruby/core/enumerator/lazy/lazy_spec.rb b/spec/ruby/core/enumerator/lazy/lazy_spec.rb
index cde9b31066..683dfb81d7 100644
--- a/spec/ruby/core/enumerator/lazy/lazy_spec.rb
+++ b/spec/ruby/core/enumerator/lazy/lazy_spec.rb
@@ -16,6 +16,10 @@ describe "Enumerator::Lazy" do
     ]
     lazy_methods += [:chunk_while, :uniq]
 
+    ruby_version_is '3.1' do
+      lazy_methods += [:compact]
+    end
+
     Enumerator::Lazy.instance_methods(false).should include(*lazy_methods)
   end
 end
@@ -26,3 +30,13 @@ describe "Enumerator::Lazy#lazy" do
     lazy.lazy.should equal(lazy)
   end
 end
+
+ruby_version_is '3.1' do
+  describe "Enumerator::Lazy#compact" do
+    it 'returns array without nil elements' do
+      arr = [1, nil, 3, false, 5].to_enum.lazy.compact
+      arr.should be_an_instance_of(Enumerator::Lazy)
+      arr.force.should == [1, 3, false, 5]
+    end
+  end
+end
diff --git a/spec/ruby/core/file/shared/fnmatch.rb b/spec/ruby/core/file/shared/fnmatch.rb
index 00682bb64c..94f22144b0 100644
--- a/spec/ruby/core/file/shared/fnmatch.rb
+++ b/spec/ruby/core/file/shared/fnmatch.rb
@@ -159,10 +159,10 @@ describe :file_fnmatch, shared: true do
   end
 
   it "does not match leading periods in filenames with wildcards by default" do
-    File.send(@method, '*', '.profile').should == false
-    File.send(@method, '*', 'home/.profile').should == true
-    File.send(@method, '*/*', 'home/.profile').should == true
-    File.send(@method, '*/*', 'dave/.profile', File::FNM_PATHNAME).should == false
+    File.should_not.send(@method, '*', '.profile')
+    File.should.send(@method, '*', 'home/.profile')
+    File.should.send(@method, '*/*', 'home/.profile')
+    File.should_not.send(@method, '*/*', 'dave/.profile', File::FNM_PATHNAME)
   end
 
   it "matches patterns with leading periods to dotfiles by default" do
diff --git a/spec/ruby/core/range/clone_spec.rb b/spec/ruby/core/range/clone_spec.rb
new file mode 100644
index 0000000000..cf6ce74da0
--- /dev/null
+++ b/spec/ruby/core/range/clone_spec.rb
@@ -0,0 +1,26 @@
+require_relative '../../spec_helper'
+
+describe "Range#clone" do
+  it "duplicates the range" do
+    original = (1..3)
+    copy = original.clone
+    copy.begin.should == 1
+    copy.end.should == 3
+    copy.should_not.exclude_end?
+    copy.should_not.equal? original
+
+    original = ("a"..."z")
+    copy = original.clone
+    copy.begin.should == "a"
+    copy.end.should == "z"
+    copy.should.exclude_end?
+    copy.should_not.equal? original
+  end
+
+  it "maintains the frozen state" do
+    (1..2).clone.frozen?.should == (1..2).frozen?
+    (1..).clone.frozen?.should == (1..).frozen?
+    Range.new(1, 2).clone.frozen?.should == Range.new(1, 2).frozen?
+    Class.new(Range).new(1, 2).clone.frozen?.should == Class.new(Range).new(1, 2).frozen?
+  end
+end
diff --git a/spec/ruby/core/range/dup_spec.rb b/spec/ruby/core/range/dup_spec.rb
index 976d4fd1d0..fab3c3f1b2 100644
--- a/spec/ruby/core/range/dup_spec.rb
+++ b/spec/ruby/core/range/dup_spec.rb
@@ -2,10 +2,12 @@ require_relative '../../spec_helper'
 
 describe "Range#dup" do
   it "duplicates the range" do
-    copy = (1..3).dup
+    original = (1..3)
+    copy = original.dup
     copy.begin.should == 1
     copy.end.should == 3
     copy.should_not.exclude_end?
+    copy.should_not.equal?(original)
 
     copy = ("a"..."z").dup
     copy.begin.should == "a"
diff --git a/spec/ruby/core/range/new_spec.rb b/spec/ruby/core/range/new_spec.rb
index 85e99babff..40df914b83 100644
--- a/spec/ruby/core/range/new_spec.rb
+++ b/spec/ruby/core/range/new_spec.rb
@@ -65,5 +65,15 @@ describe "Range.new" do
 
       range_exclude.should_not == range_include
     end
+
+    ruby_version_is "3.0" do
+      it "creates a frozen range if the class is Range.class" do
+        Range.new(1, 2).should.frozen?
+      end
+
+      it "does not create a frozen range if the class is not Range.class" do
+        Class.new(Range).new(1, 2).should_not.frozen?
+      end
+    end
   end
 end
diff --git a/spec/ruby/core/regexp/shared/quote.rb b/spec/ruby/core/regexp/shared/quote.rb
index 33bdfd9979..9533102766 100644
--- a/spec/ruby/core/regexp/shared/quote.rb
+++ b/spec/ruby/core/regexp/shared/quote.rb
@@ -17,6 +17,11 @@ describe :regexp_quote, shared: true do
     Regexp.send(@method, str).should == '\+\[\]\('
   end
 
+  it "works for broken strings" do
+    Regexp.send(@method, "a.\x85b.".force_encoding("US-ASCII")).should =="a\\.\x85b\\.".force_encoding("US-ASCII")
+    Regexp.send(@method, "a.\x80".force_encoding("UTF-8")).should == "a\\.\x80".force_encoding("UTF-8")
+  end
+
   it "sets the encoding of the result to US-ASCII if there are only US-ASCII characters present in the input String" do
     str = "abc".force_encoding("euc-jp")
     Regexp.send(@method, str).encoding.should == Encoding::US_ASCII
diff --git a/spec/ruby/core/regexp/source_spec.rb b/spec/ruby/core/regexp/source_spec.rb
index 709fee49b3..5f253da9ea 100644
--- a/spec/ruby/core/regexp/source_spec.rb
+++ b/spec/ruby/core/regexp/source_spec.rb
@@ -9,8 +9,26 @@ describe "Regexp#source" do
     /x(.)xz/.source.should == "x(.)xz"
   end
 
-  it "will remove escape characters" do
-    /foo\/bar/.source.should == "foo/bar"
+  it "keeps escape sequences as is" do
+    /\x20\+/.source.should == '\x20\+'
+  end
+
+  describe "escaping" do
+    it "keeps escaping of metacharacter" do
+      /\$/.source.should == "\\$"
+    end
+
+    it "keeps escaping of metacharacter used as a terminator" do
+      %r+\++.source.should == "\\+"
+    end
+
+    it "removes escaping of non-metacharacter used as a terminator" do
+      %r@\@@.source.should == "@"
+    end
+
+    it "keeps escaping of non-metacharacter not used as a terminator" do
+      /\@/.source.should == "\\@"
+    end
   end
 
   not_supported_on :opal do
diff --git a/spec/ruby/core/string/capitalize_spec.rb b/spec/ruby/core/string/capitalize_spec.rb
index 8afaefc021..751f4160a6 100644
--- a/spec/ruby/core/string/capitalize_spec.rb
+++ b/spec/ruby/core/string/capitalize_spec.rb
@@ -10,6 +10,7 @@ describe "String#capitalize" do
     "hello".capitalize.should == "Hello"
     "HELLO".capitalize.should == "Hello"
     "123ABC".capitalize.should == "123abc"
+    "abcdef"[1...-1].capitalize.should == "Bcde"
   end
 
   describe "full Unicode case mapping" do
@@ -37,7 +38,7 @@ describe "String#capitalize" do
     end
 
     it "handles non-ASCII substrings properly" do
-      "garçon"[1..-1].capitalize(:ascii).should == "Arçon"
+      "garçon"[1...-1].capitalize(:ascii).should == "Arço"
     end
   end
 
diff --git a/spec/ruby/core/string/delete_prefix_spec.rb b/spec/ruby/core/string/delete_prefix_spec.rb
index a063e443d8..17ce18bcca 100644
--- a/spec/ruby/core/string/delete_prefix_spec.rb
+++ b/spec/ruby/core/string/delete_prefix_spec.rb
@@ -21,6 +21,10 @@ describe "String#delete_prefix" do
     r.should == s
   end
 
+  it "does not remove partial bytes, only full characters" do
+    "\xe3\x81\x82".delete_prefix("\xe3").should == "\xe3\x81\x82"
+  end
+
   it "doesn't set $~" do
     $~ = nil
 
diff --git a/spec/ruby/core/string/delete_suffix_spec.rb b/spec/ruby/core/string/delete_suffix_spec.rb
index 3d3274bc5b..0705c73246 100644
--- a/spec/ruby/core/string/delete_suffix_spec.rb
+++ b/spec/ruby/core/string/delete_suffix_spec.rb
@@ -21,6 +21,10 @@ describe "String#delete_suffix" do
     r.should == s
   end
 
+  it "does not remove partial bytes, only full characters" do
+    "\xe3\x81\x82".delete_suffix("\x82").should == "\xe3\x81\x82"
+  end
+
   it "doesn't set $~" do
     $~ = nil
 
diff --git a/spec/ruby/core/string/downcase_spec.rb b/spec/ruby/core/string/downcase_spec.rb
index 86d8480889..f0a15f1e25 100644
--- a/spec/ruby/core/string/downcase_spec.rb
+++ b/spec/ruby/core/string/downcase_spec.rb
@@ -27,6 +27,10 @@ describe "String#downcase" do
     it "does not downcase non-ASCII characters" do
       "CÅR".downcase(:ascii).should == "cÅr"
     end
+
+    it "works with substrings" do
+      "prefix TÉ"[-2..-1].downcase(:ascii).should == "tÉ"
+    end
   end
 
   describe "full Unicode case mapping adapted for Turkic languages" do
diff --git a/spec/ruby/core/string/encoding_spec.rb b/spec/ruby/core/string/encoding_spec.rb
index 4d17a39f29..574a1e2f92 100644
--- a/spec/ruby/core/string/encoding_spec.rb
+++ b/spec/ruby/core/string/encoding_spec.rb
@@ -10,6 +10,7 @@ describe "String#encoding" do
   it "is equal to the source encoding by default" do
     s = StringSpecs::ISO88599Encoding.new
     s.cedilla.encoding.should == s.source_encoding
+    s.cedilla.encode("utf-8").should == 350.chr(Encoding::UTF_8) # S-cedilla
   end
 
   it "returns the given encoding if #force_encoding has been called" do
diff --git a/spec/ruby/core/string/fixtures/iso-8859-9-encoding.rb b/spec/ruby/core/string/fixtures/iso-8859-9-encoding.rb
index 61a691ff78..cfa91dedc3 100644
--- a/spec/ruby/core/string/fixtures/iso-8859-9-encoding.rb
+++ b/spec/ruby/core/string/fixtures/iso-8859-9-encoding.rb
@@ -4,6 +4,6 @@ module StringSpecs
     def source_encoding; __ENCODING__; end
     def x_escape; [0xDF].pack('C').force_encoding("iso-8859-9"); end
     def ascii_only; "glark"; end
-    def cedilla; "Ş"; end
+    def cedilla; "�"; end # S-cedilla
   end
 end
diff --git a/spec/ruby/core/string/include_spec.rb b/spec/ruby/core/string/include_spec.rb
index e32eb17c29..23e1e134ec 100644
--- a/spec/ruby/core/string/include_spec.rb
+++ b/spec/ruby/core/string/include_spec.rb
@@ -13,6 +13,20 @@ describe "String#include? with String" do
     StringSpecs::MyString.new("hello").include?(StringSpecs::MyString.new("lo")).should == true
   end
 
+  it "returns true if both strings are empty" do
+    "".should.include?("")
+    "".force_encoding("EUC-JP").should.include?("")
+    "".should.include?("".force_encoding("EUC-JP"))
+    "".force_encoding("EUC-JP").should.include?("".force_encoding("EUC-JP"))
+  end
+
+  it "returns true if the RHS is empty" do
+    "a".should.include?("")
+    "a".force_encoding("EUC-JP").should.include?("")
+    "a".should.include?("".force_encoding("EUC-JP"))
+    "a".force_encoding("EUC-JP").should.include?("".force_encoding("EUC-JP"))
+  end
+
   it "tries to convert other to string using to_str" do
     other = mock('lo')
     other.should_receive(:to_str).and_return("lo")
diff --git a/spec/ruby/core/string/inspect_spec.rb b/spec/ruby/core/string/inspect_spec.rb
index 8bfd465144..8bf3d3161f 100644
--- a/spec/ruby/core/string/inspect_spec.rb
+++ b/spec/ruby/core/string/inspect_spec.rb
@@ -19,6 +19,21 @@ describe "String#inspect" do
     ].should be_computed_by(:inspect)
   end
 
+  it "returns a string with special characters replaced with \\<char> notation for UTF-16" do
+    pairs = [
+      ["\a", '"\\a"'],
+      ["\b", '"\\b"'],
+      ["\t", '"\\t"'],
+      ["\n", '"\\n"'],
+      ["\v", '"\\v"'],
+      ["\f", '"\\f"'],
+      ["\r", '"\\r"'],
+      ["\e", '"\\e"']
+    ].map { |str, result| [str.encode('UTF-16LE'), result] }
+
+    pairs.should be_computed_by(:inspect)
+  end
+
   it "returns a string with \" and \\ escaped with a backslash" do
     [ ["\"", '"\\""'],
       ["\\", '"\\\\"']
@@ -311,6 +326,11 @@ describe "String#inspect" do
     "\xF0\x9F".inspect.should == '"\\xF0\\x9F"'
   end
 
+  it "works for broken US-ASCII strings" do
+    s = "©".force_encoding("US-ASCII")
+    s.inspect.should == '"\xC2\xA9"'
+  end
+
   describe "when default external is UTF-8" do
     before :each do
       @extenc, Encoding.default_external = Encoding.default_external, Encoding::UTF_8
diff --git a/spec/ruby/core/string/lstrip_spec.rb b/spec/ruby/core/string/lstrip_spec.rb
index 02bc6b4322..75434613f1 100644
--- a/spec/ruby/core/string/lstrip_spec.rb
+++ b/spec/ruby/core/string/lstrip_spec.rb
@@ -10,6 +10,14 @@ describe "String#lstrip" do
    "  hello world  ".lstrip.should == "hello world  "
    "\n\r\t\n\v\r hello world  ".lstrip.should == "hello world  "
    "hello".lstrip.should == "hello"
+   " こにちわ".lstrip.should == "こにちわ"
+  end
+
+  it "works with lazy substrings" do
+    "  hello  "[1...-1].lstrip.should == "hello "
+    "  hello world  "[1...-1].lstrip.should == "hello world "
+    "\n\r\t\n\v\r hello world  "[1...-1].lstrip.should == "hello world "
+    "   こにちわ "[1...-1].lstrip.should == "こにちわ"
   end
 
   ruby_version_is '3.0' do
@@ -27,20 +35,26 @@ describe "String#lstrip!" do
     a.should == "hello  "
   end
 
+  it "returns nil if no modifications were made" do
+    a = "hello"
+    a.lstrip!.should == nil
+    a.should == "hello"
+  end
+
+  it "makes a string empty if it is only whitespace" do
+    "".lstrip!.should == nil
+    " ".lstrip.should == ""
+    "  ".lstrip.should == ""
+  end
+
   ruby_version_is '3.0' do
-    it "strips leading \\0" do
+    it "removes leading NULL bytes and whitespace" do
       a = "\000 \000hello\000 \000"
       a.lstrip!
       a.should == "hello\000 \000"
     end
   end
 
-  it "returns nil if no modifications were made" do
-    a = "hello"
-    a.lstrip!.should == nil
-    a.should == "hello"
-  end
-
   it "raises a FrozenError on a frozen instance that is modified" do
     -> { "  hello  ".freeze.lstrip! }.should raise_error(FrozenError)
   end
@@ -51,9 +65,13 @@ describe "String#lstrip!" do
     -> { "".freeze.lstrip!      }.should raise_error(FrozenError)
   end
 
-  it "raises an ArgumentError if the first codepoint is invalid" do
+  it "raises an ArgumentError if the first non-space codepoint is invalid" do
     s = "\xDFabc".force_encoding(Encoding::UTF_8)
     s.valid_encoding?.should be_false
     -> { s.lstrip! }.should raise_error(ArgumentError)
+
+    s = "   \xDFabc".force_encoding(Encoding::UTF_8)
+    s.valid_encoding?.should be_false
+    -> { s.lstrip! }.should raise_error(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/string/ord_spec.rb b/spec/ruby/core/string/ord_spec.rb
index cfc630a124..4cf26990fe 100644
--- a/spec/ruby/core/string/ord_spec.rb
+++ b/spec/ruby/core/string/ord_spec.rb
@@ -25,4 +25,9 @@ describe "String#ord" do
   it "raises an ArgumentError if called on an empty String" do
     -> { ''.ord }.should raise_error(ArgumentError)
   end
+
+  it "raises ArgumentError if the character is broken" do
+    s = "©".force_encoding("US-ASCII")
+    -> { s.ord }.should raise_error(ArgumentError, "invalid byte sequence in US-ASCII")
+  end
 end
diff --git a/spec/ruby/core/string/reverse_spec.rb b/spec/ruby/core/string/reverse_spec.rb
index bade4685d9..4206b8af90 100644
--- a/spec/ruby/core/string/reverse_spec.rb
+++ b/spec/ruby/core/string/reverse_spec.rb
@@ -29,6 +29,14 @@ describe "String#reverse" do
   it "reverses a string with multi byte characters" do
     "微軟正黑體".reverse.should == "體黑正軟微"
   end
+
+  it "works with a broken string" do
+    str = "微軟\xDF\xDE正黑體".force_encoding(Encoding::UTF_8)
+
+    str.valid_encoding?.should be_false
+
+    str.reverse.should == "體黑正\xDE\xDF軟微"
+  end
 end
 
 describe "String#reverse!" do
@@ -55,4 +63,13 @@ describe "String#reverse!" do
     str.reverse!
     str.should == "體黑正軟微"
   end
+
+  it "works with a broken string" do
+    str = "微軟\xDF\xDE正黑體".force_encoding(Encoding::UTF_8)
+
+    str.valid_encoding?.should be_false
+    str.reverse!
+
+    str.should == "體黑正\xDE\xDF軟微"
+  end
 end
diff --git a/spec/ruby/core/string/rstrip_spec.rb b/spec/ruby/core/string/rstrip_spec.rb
index dc34b12719..4332b33b20 100644
--- a/spec/ruby/core/string/rstrip_spec.rb
+++ b/spec/ruby/core/string/rstrip_spec.rb
@@ -11,6 +11,14 @@ describe "String#rstrip" do
     "  hello world \n\r\t\n\v\r".rstrip.should == "  hello world"
     "hello".rstrip.should == "hello"
     "hello\x00".rstrip.should == "hello"
+    "こにちわ ".rstrip.should == "こにちわ"
+  end
+
+  it "works with lazy substrings" do
+    "  hello  "[1...-1].rstrip.should == " hello"
+    "  hello world  "[1...-1].rstrip.should == " hello world"
+    "  hello world \n\r\t\n\v\r"[1...-1].rstrip.should == " hello world"
+    " こにちわ  "[1...-1].rstrip.should == "こにちわ"
   end
 
   it "returns a copy of self with all trailing whitespace and NULL bytes removed" do
@@ -37,6 +45,20 @@ describe "String#rstrip!" do
     a.should == "hello"
   end
 
+  it "makes a string empty if it is only whitespace" do
+    "".rstrip!.should == nil
+    " ".rstrip.should == ""
+    "  ".rstrip.should == ""
+  end
+
+  ruby_version_is '3.0' do
+    it "removes trailing NULL bytes and whitespace" do
+      a = "\000 goodbye \000"
+      a.rstrip!
+      a.should == "\000 goodbye"
+    end
+  end
+
   it "raises a FrozenError on a frozen instance that is modified" do
     -> { "  hello  ".freeze.rstrip! }.should raise_error(FrozenError)
   end
@@ -47,9 +69,13 @@ describe "String#rstrip!" do
     -> { "".freeze.rstrip!      }.should raise_error(FrozenError)
   end
 
-  it "raises an ArgumentError if the last codepoint is invalid" do
+  it "raises an ArgumentError if the last non-space codepoint is invalid" do
     s = "abc\xDF".force_encoding(Encoding::UTF_8)
     s.valid_encoding?.should be_false
     -> { s.rstrip! }.should raise_error(ArgumentError)
+
+    s = "abc\xDF   ".force_encoding(Encoding::UTF_8)
+    s.valid_encoding?.should be_false
+    -> { s.rstrip! }.should raise_error(ArgumentError)
   end
 end
diff --git a/spec/ruby/core/string/setbyte_spec.rb b/spec/ruby/core/string/setbyte_spec.rb
index 03e5bad88b..77bff64038 100644
--- a/spec/ruby/core/string/setbyte_spec.rb
+++ b/spec/ruby/core/string/setbyte_spec.rb
@@ -36,6 +36,12 @@ describe "String#setbyte" do
     str.valid_encoding?.should be_true
     str.setbyte(2,253)
     str.valid_encoding?.should be_false
+
+    str = "ABC"
+    str.setbyte(0, 0x20) # ' '
+    str.should.valid_encoding?
+    str.setbyte(0, 0xE3)
+    str.should_not.valid_encoding?
   end
 
   it "regards a negative index as counting from the end of the String" do
diff --git a/spec/ruby/core/string/shared/dedup.rb b/spec/ruby/core/string/shared/dedup.rb
index 345e874583..6ffcb9b045 100644
--- a/spec/ruby/core/string/shared/dedup.rb
+++ b/spec/ruby/core/string/shared/dedup.rb
@@ -38,6 +38,16 @@ describe :string_dedup, shared: true do
     dynamic.send(@method).should equal("this string is frozen".send(@method).freeze)
   end
 
+  it "does not deduplicate a frozen string when it has instance variables" do
+    dynamic = %w(this string is frozen).join(' ')
+    dynamic.instance_variable_set(:@a, 1)
+    dynamic.freeze
+
+    dynamic.send(@method).should_not equal("this string is frozen".freeze)
+    dynamic.send(@method).should_not equal("this string is frozen".send(@method).freeze)
+    dynamic.send(@method).should equal(dynamic)
+  end
+
   ruby_version_is "3.0" do
     it "interns the provided string if it is frozen" do
       dynamic = "this string is unique and frozen #{rand}".freeze
diff --git a/spec/ruby/core/string/split_spec.rb b/spec/ruby/core/string/split_spec.rb
index 7ef34c65da..b57f660816 100644
--- a/spec/ruby/core/string/split_spec.rb
+++ b/spec/ruby/core/string/split_spec.rb
@@ -455,6 +455,14 @@ describe "String#split with Regexp" do
       a.should == ["Chunky", "Bacon"]
     end
 
+    it "yields each split substring with default pattern for a lazy substring" do
+      a = []
+      returned_object = "chunky bacon"[1...-1].split { |str| a << str.capitalize }
+
+      returned_object.should == "hunky baco"
+      a.should == ["Hunky", "Baco"]
+    end
+
     it "yields each split substring with default pattern for a non-ASCII string" do
       a = []
       returned_object = "l'été arrive bientôt".split { |str| a << str }
@@ -463,6 +471,14 @@ describe "String#split with Regexp" do
       a.should == ["l'été", "arrive", "bientôt"]
     end
 
+    it "yields each split substring with default pattern for a non-ASCII lazy substring" do
+      a = []
+      returned_object = "l'été arrive bientôt"[1...-1].split { |str| a << str }
+
+      returned_object.should == "'été arrive bientô"
+      a.should == ["'été", "arrive", "bientô"]
+    end
+
     it "yields the string when limit is 1" do
       a = []
       returned_object = "chunky bacon".split("", 1) { |str| a << str.capitalize }
diff --git a/spec/ruby/core/string/start_with_spec.rb b/spec/ruby/core/string/start_with_spec.rb
index aaed197ff3..3833289f96 100644
--- a/spec/ruby/core/string/start_with_spec.rb
+++ b/spec/ruby/core/string/start_with_spec.rb
@@ -5,4 +5,14 @@ require_relative '../../shared/string/start_with'
 
 describe "String#start_with?" do
   it_behaves_like :start_with, :to_s
+
+  # Here and not in the shared examples because this is invalid as a Symbol
+  it "does not check that we are not starting to match at the head of a character" do
+    "\xA9".should.start_with?("\xA9") # A9 is not a character head for UTF-8
+  end
+
+  it "does not check we are matching only part of a character" do
+    "\xe3\x81\x82".size.should == 1
+    "\xe3\x81\x82".should.start_with?("\xe3")
+  end
 end
diff --git a/spec/ruby/core/string/strip_spec.rb b/spec/ruby/core/string/strip_spec.rb
index e841db54ce..662f13b032 100644
--- a/spec/ruby/core/string/strip_spec.rb
+++ b/spec/ruby/core/string/strip_spec.rb
@@ -35,6 +35,12 @@ describe "String#strip!" do
     a.should == "hello"
   end
 
+  it "makes a string empty if it is only whitespace" do
+    "".strip!.should == nil
+    " ".strip.should == ""
+    "  ".strip.should == ""
+  end
+
   ruby_version_is '3.0' do
     it "removes leading and trailing NULL bytes and whitespace" do
       a = "\000 goodbye \000"
diff --git a/spec/ruby/core/string/swapcase_spec.rb b/spec/ruby/core/string/swapcase_spec.rb
index 417f6c6d8d..6307a1eaaf 100644
--- a/spec/ruby/core/string/swapcase_spec.rb
+++ b/spec/ruby/core/string/swapcase_spec.rb
@@ -28,6 +28,10 @@ describe "String#swapcase" do
     it "does not swapcase non-ASCII characters" do
       "aßet".swapcase(:ascii).should == "AßET"
     end
+
+    it "works with substrings" do
+      "prefix aTé"[-3..-1].swapcase(:ascii).should == "Até"
+    end
   end
 
   describe "full Unicode case mapping adapted for Turkic languages" do
diff --git a/spec/ruby/core/string/upcase_spec.rb b/spec/ruby/core/string/upcase_spec.rb
index b2b34190fe..209fe73b6e 100644
--- a/spec/ruby/core/string/upcase_spec.rb
+++ b/spec/ruby/core/string/upcase_spec.rb
@@ -27,6 +27,10 @@ describe "String#upcase" do
     it "does not upcase non-ASCII characters" do
       "aßet".upcase(:ascii).should == "AßET"
     end
+
+    it "works with substrings" do
+      "prefix té"[-2..-1].upcase(:ascii).should == "Té"
+    end
   end
 
   describe "full Unicode case mapping adapted for Turkic languages" do
diff --git a/spec/ruby/language/range_spec.rb b/spec/ruby/language/range_spec.rb
index 55dc65882a..ccc9f55537 100644
--- a/spec/ruby/language/range_spec.rb
+++ b/spec/ruby/language/range_spec.rb
@@ -10,6 +10,14 @@ describe "Literal Ranges" do
     (1...10).should == Range.new(1, 10, true)
   end
 
+  it "creates a simple range as an object literal" do
+    ary = []
+    2.times do
+      ary.push(1..3)
+    end
+    ary[0].should.equal?(ary[1])
+  end
+
   it "creates endless ranges" do
     (1..).should == Range.new(1, nil)
     (1...).should == Range.new(1, nil, true)
diff --git a/spec/ruby/language/regexp/escapes_spec.rb b/spec/ruby/language/regexp/escapes_spec.rb
index 2e5fe5ad2e..16a4d8c23b 100644
--- a/spec/ruby/language/regexp/escapes_spec.rb
+++ b/spec/ruby/language/regexp/escapes_spec.rb
@@ -2,8 +2,10 @@
 require_relative '../../spec_helper'
 require_relative '../fixtures/classes'
 
+# TODO: synchronize with spec/core/regexp/new_spec.rb -
+#       escaping is also tested there
 describe "Regexps with escape characters" do
-  it "they're supported" do
+  it "supports escape sequences" do
     /\t/.match("\t").to_a.should == ["\t"] # horizontal tab
     /\v/.match("\v").to_a.should == ["\v"] # vertical tab
     /\n/.match("\n").to_a.should == ["\n"] # newline
@@ -15,9 +17,7 @@ describe "Regexps with escape characters" do
     # \nnn         octal char            (encoded byte value)
   end
 
-  it "support quoting meta-characters via escape sequence" do
-    /\\/.match("\\").to_a.should == ["\\"]
-    /\//.match("/").to_a.should == ["/"]
+  it "supports quoting meta-characters via escape sequence" do
     # parenthesis, etc
     /\(/.match("(").to_a.should == ["("]
     /\)/.match(")").to_a.should == [")"]
@@ -25,6 +25,8 @@ describe "Regexps with escape characters" do
     /\]/.match("]").to_a.should == ["]"]
     /\{/.match("{").to_a.should == ["{"]
     /\}/.match("}").to_a.should == ["}"]
+    /\</.match("<").to_a.should == ["<"]
+    /\>/.match(">").to_a.should == [">"]
     # alternation separator
     /\|/.match("|").to_a.should == ["|"]
     # quantifiers
@@ -37,11 +39,81 @@ describe "Regexps with escape characters" do
     /\$/.match("$").to_a.should == ["$"]
   end
 
+  it "supports quoting meta-characters via escape sequence when used as a terminator" do
+    # parenthesis, etc
+    # %r[[, %r((, etc literals - are forbidden
+    %r(\().match("(").to_a.should == ["("]
+    %r(\)).match(")").to_a.should == [")"]
+    %r)\().match("(").to_a.should == ["("]
+    %r)\)).match(")").to_a.should == [")"]
+
+    %r[\[].match("[").to_a.should == ["["]
+    %r[\]].match("]").to_a.should == ["]"]
+    %r]\[].match("[").to_a.should == ["["]
+    %r]\]].match("]").to_a.should == ["]"]
+
+    %r{\{}.match("{").to_a.should == ["{"]
+    %r{\}}.match("}").to_a.should == ["}"]
+    %r}\{}.match("{").to_a.should == ["{"]
+    %r}\}}.match("}").to_a.should == ["}"]
+
+    %r<\<>.match("<").to_a.should == ["<"]
+    %r<\>>.match(">").to_a.should == [">"]
+    %r>\<>.match("<").to_a.should == ["<"]
+    %r>\>>.match(">").to_a.should == [">"]
+
+    # alternation separator
+    %r|\||.match("|").to_a.should == ["|"]
+    # quantifiers
+    %r?\??.match("?").to_a.should == ["?"]
+    %r.\...match(".").to_a.should == ["."]
+    %r*\**.match("*").to_a.should == ["*"]
+    %r+\++.match("+").to_a.should == ["+"]
+    # line anchors
+    %r^\^^.match("^").to_a.should == ["^"]
+    %r$\$$.match("$").to_a.should == ["$"]
+  end
+
+  it "supports quoting non-meta-characters via escape sequence when used as a terminator" do
+    non_meta_character_terminators = [
+      '!', '"', '#', '%', '&', "'", ',', '-', ':', ';', '@', '_', '`', '/', '=', '~'
+    ]
+
+    non_meta_character_terminators.each do |c|
+      pattern = eval("%r" + c + "\\" + c + c)
+      pattern.match(c).to_a.should == [c]
+    end
+  end
+
+  it "does not change semantics of escaped non-meta-character when used as a terminator" do
+    all_terminators = [*("!".."/"), *(":".."@"), *("[".."`"), *("{".."~")]
+    meta_character_terminators = ["$", "^", "*", "+", ".", "?", "|", "}", ")", ">", "]"]
+    special_cases = ['(', '{', '[', '<', '\\']
+
+    # it should be equivalent to
+    #   [ '!', '"', '#', '%', '&', "'", ',', '-', ':', ';', '@', '_', '`', '/', '=', '~' ]
+    non_meta_character_terminators = all_terminators - meta_character_terminators - special_cases
+
+    non_meta_character_terminators.each do |c|
+      pattern = eval("%r" + c + "\\" + c + c)
+      pattern.should == /#{c}/
+    end
+  end
+
+  it "does not change semantics of escaped meta-character when used as a terminator" do
+    meta_character_terminators = ["$", "^", "*", "+", ".", "?", "|", "}", ")", ">", "]"]
+
+    meta_character_terminators.each do |c|
+      pattern = eval("%r" + c + "\\" + c + c)
+      pattern.should == eval("/\\#{c}/")
+    end
+  end
+
   it "allows any character to be escaped" do
     /\y/.match("y").to_a.should == ["y"]
   end
 
-  it "support \\x (hex characters)" do
+  it "supports \\x (hex characters)" do
     /\xA/.match("\nxyz").to_a.should == ["\n"]
     /\x0A/.match("\n").to_a.should == ["\n"]
     /\xAA/.match("\nA").should be_nil
@@ -53,7 +125,7 @@ describe "Regexps with escape characters" do
     # \x{7HHHHHHH} wide hexadecimal char (character code point value)
   end
 
-  it "support \\c (control characters)" do
+  it "supports \\c (control characters)" do
     #/\c \c@\c`/.match("\00\00\00").to_a.should == ["\00\00\00"]
     /\c#\cc\cC/.match("\03\03\03").to_a.should == ["\03\03\03"]
     /\c'\cG\cg/.match("\a\a\a").to_a.should == ["\a\a\a"]
diff --git a/spec/ruby/language/regexp_spec.rb b/spec/ruby/language/regexp_spec.rb
index 8fc4dc4f0a..d49689349d 100644
--- a/spec/ruby/language/regexp_spec.rb
+++ b/spec/ruby/language/regexp_spec.rb
@@ -96,7 +96,6 @@ describe "Literal Regexps" do
     /./.match("\0").to_a.should == ["\0"]
   end
 
-
   it "supports | (alternations)" do
     /a|b/.match("a").to_a.should == ["a"]
   end
@@ -161,26 +160,6 @@ describe "Literal Regexps" do
     pattern.should_not =~ 'T'
   end
 
-  escapable_terminators =  ['!', '"', '#', '%', '&', "'", ',', '-', ':', ';', '@', '_', '`']
-
-  it "supports escaping characters when used as a terminator" do
-    escapable_terminators.each do |c|
-      ref = "(?-mix:#{c})"
-      pattern = eval("%r" + c + "\\" + c + c)
-      pattern.to_s.should == ref
-    end
-  end
-
-  it "treats an escaped non-escapable character normally when used as a terminator" do
-    all_terminators = [*("!".."/"), *(":".."@"), *("[".."`"), *("{".."~")]
-    special_cases = ['(', '{', '[', '<', '\\', '=', '~']
-    (all_terminators - special_cases - escapable_terminators).each do |c|
-      ref = "(?-mix:\\#{c})"
-      pattern = eval("%r" + c + "\\" + c + c)
-      pattern.to_s.should == ref
-    end
-  end
-
   it "support handling unicode 9.0 characters with POSIX bracket expressions" do
     char_lowercase = "\u{104D8}" # OSAGE SMALL LETTER A
     /[[:lower:]]/.match(char_lowercase).to_s.should == char_lowercase
diff --git a/spec/ruby/library/stringio/shared/read.rb b/spec/ruby/library/stringio/shared/read.rb
index c60677bba7..252a85d89d 100644
--- a/spec/ruby/library/stringio/shared/read.rb
+++ b/spec/ruby/library/stringio/shared/read.rb
@@ -89,6 +89,12 @@ describe :stringio_read_no_arguments, shared: true do
     @io.send(@method)
     @io.pos.should eql(7)
   end
+
+  it "correctly update the current position in bytes when multi-byte characters are used" do
+    @io.print("example\u03A3") # Overwrite the original string with 8 characters containing 9 bytes.
+    @io.send(@method)
+    @io.pos.should eql(9)
+  end
 end
 
 describe :stringio_read_nil, shared: true do
diff --git a/spec/ruby/optional/capi/encoding_spec.rb b/spec/ruby/optional/capi/encoding_spec.rb
index e18108c022..ae557b03d7 100644
--- a/spec/ruby/optional/capi/encoding_spec.rb
+++ b/spec/ruby/optional/capi/encoding_spec.rb
@@ -128,10 +128,16 @@ describe "C-API Encoding function" do
 
   describe "rb_enc_mbc_to_codepoint" do
     it "returns the correct codepoint for the given character and size" do
-       @s.rb_enc_mbc_to_codepoint("é", 2).should == 0x00E9
-       @s.rb_enc_mbc_to_codepoint("éa", 2).should == 0x00E9
-       @s.rb_enc_mbc_to_codepoint("éa", 1).should == 0xC3
-       @s.rb_enc_mbc_to_codepoint("éa", 3).should == 0x00E9
+       @s.rb_enc_mbc_to_codepoint("é").should == 0xE9
+    end
+
+    it "returns 0 if p == e" do
+      @s.rb_enc_mbc_to_codepoint("").should == 0
+    end
+
+    it "returns the raw byte if incomplete character in UTF-8" do
+      @s.rb_enc_mbc_to_codepoint("\xC3").should == 0xC3
+      @s.rb_enc_mbc_to_codepoint("\x80").should == 0x80
     end
   end
 
@@ -630,6 +636,7 @@ describe "C-API Encoding function" do
     it "returns the correct case fold for the given string" do
       @s.ONIGENC_MBC_CASE_FOLD("lower").should == ["l", 1]
       @s.ONIGENC_MBC_CASE_FOLD("Upper").should == ["u", 1]
+      @s.ONIGENC_MBC_CASE_FOLD("ABC"[1..-1]).should == ["b", 1]
     end
 
     it "works with other encodings" do
diff --git a/spec/ruby/optional/capi/ext/encoding_spec.c b/spec/ruby/optional/capi/ext/encoding_spec.c
index 68c4161bab..c49f6cde7e 100644
--- a/spec/ruby/optional/capi/ext/encoding_spec.c
+++ b/spec/ruby/optional/capi/ext/encoding_spec.c
@@ -120,10 +120,9 @@ static VALUE encoding_spec_rb_enc_from_index(VALUE self, VALUE index) {
   return rb_str_new2(rb_enc_from_index(NUM2INT(index))->name);
 }
 
-static VALUE encoding_spec_rb_enc_mbc_to_codepoint(VALUE self, VALUE str, VALUE offset) {
-  int o = FIX2INT(offset);
+static VALUE encoding_spec_rb_enc_mbc_to_codepoint(VALUE self, VALUE str) {
   char *p = RSTRING_PTR(str);
-  char *e = p + o;
+  char *e = RSTRING_END(str);
   return INT2FIX(rb_enc_mbc_to_codepoint(p, e, rb_enc_get(str)));
 }
 
@@ -341,7 +340,7 @@ void Init_encoding_spec(void) {
   rb_define_method(cls, "rb_enc_isalnum", encoding_spec_rb_enc_isalnum, 2);
   rb_define_method(cls, "rb_enc_isspace", encoding_spec_rb_enc_isspace, 2);
   rb_define_method(cls, "rb_enc_from_index", encoding_spec_rb_enc_from_index, 1);
-  rb_define_method(cls, "rb_enc_mbc_to_codepoint", encoding_spec_rb_enc_mbc_to_codepoint, 2);
+  rb_define_method(cls, "rb_enc_mbc_to_codepoint", encoding_spec_rb_enc_mbc_to_codepoint, 1);
   rb_define_method(cls, "rb_enc_mbcput", encoding_spec_rb_enc_mbcput, 2);
   rb_define_method(cls, "rb_enc_from_encoding", encoding_spec_rb_enc_from_encoding, 1);
   rb_define_method(cls, "rb_enc_get", encoding_spec_rb_enc_get, 1);
diff --git a/spec/ruby/shared/file/executable.rb b/spec/ruby/shared/file/executable.rb
index 7b5c4c580c..baa156de98 100644
--- a/spec/ruby/shared/file/executable.rb
+++ b/spec/ruby/shared/file/executable.rb
@@ -39,6 +39,41 @@ describe :file_executable, shared: true do
     -> { @object.send(@method, nil)   }.should raise_error(TypeError)
     -> { @object.send(@method, false) }.should raise_error(TypeError)
   end
+
+  platform_is_not :windows do
+    as_superuser do
+      context "when run by a superuser" do
+        before :each do
+          @file = tmp('temp3.txt')
+          touch @file
+        end
+
+        after :each do
+          rm_r @file
+        end
+
+        it "returns true if file owner has permission to execute" do
+          File.chmod(0766, @file)
+          @object.send(@method, @file).should == true
+        end
+
+        it "returns true if group has permission to execute" do
+          File.chmod(0676, @file)
+          @object.send(@method, @file).should == true
+        end
+
+        it "returns true if other have permission to execute" do
+          File.chmod(0667, @file)
+          @object.send(@method, @file).should == true
+        end
+
+        it "return false if nobody has permission to execute" do
+          File.chmod(0666, @file)
+          @object.send(@method, @file).should == false
+        end
+      end
+    end
+  end
 end
 
 describe :file_executable_missing, shared: true do
diff --git a/spec/ruby/shared/file/executable_real.rb b/spec/ruby/shared/file/executable_real.rb
index ce3d5ca176..bf2734ea07 100644
--- a/spec/ruby/shared/file/executable_real.rb
+++ b/spec/ruby/shared/file/executable_real.rb
@@ -37,6 +37,41 @@ describe :file_executable_real, shared: true do
     -> { @object.send(@method, nil)   }.should raise_error(TypeError)
     -> { @object.send(@method, false) }.should raise_error(TypeError)
   end
+
+  platform_is_not :windows do
+    as_real_superuser do
+      context "when run by a real superuser" do
+        before :each do
+          @file = tmp('temp3.txt')
+          touch @file
+        end
+
+        after :each do
+          rm_r @file
+        end
+
+        it "returns true if file owner has permission to execute" do
+          File.chmod(0766, @file)
+          @object.send(@method, @file).should == true
+        end
+
+        it "returns true if group has permission to execute" do
+          File.chmod(0676, @file)
+          @object.send(@method, @file).should == true
+        end
+
+        it "returns true if other have permission to execute" do
+          File.chmod(0667, @file)
+          @object.send(@method, @file).should == true
+        end
+
+        it "return false if nobody has permission to execute" do
+          File.chmod(0666, @file)
+          @object.send(@method, @file).should == false
+        end
+      end
+    end
+  end
 end
 
 describe :file_executable_real_missing, shared: true do
diff --git a/spec/ruby/shared/file/readable.rb b/spec/ruby/shared/file/readable.rb
index eb2ca06812..7b45e23e36 100644
--- a/spec/ruby/shared/file/readable.rb
+++ b/spec/ruby/shared/file/readable.rb
@@ -24,6 +24,22 @@ describe :file_readable, shared: true do
   it "accepts an object that has a #to_path method" do
     @object.send(@method, mock_to_path(@file2)).should == true
   end
+
+  platform_is_not :windows do
+    as_superuser do
+      context "when run by a superuser" do
+        it "returns true unconditionally" do
+          file = tmp('temp.txt')
+          touch file
+
+          File.chmod(0333, file)
+          @object.send(@method, file).should == true
+
+          rm_r file
+        end
+      end
+    end
+  end
 end
 
 describe :file_readable_missing, shared: true do
diff --git a/spec/ruby/shared/file/readable_real.rb b/spec/ruby/shared/file/readable_real.rb
index b6e53ac76d..32d38bc7a2 100644
--- a/spec/ruby/shared/file/readable_real.rb
+++ b/spec/ruby/shared/file/readable_real.rb
@@ -14,6 +14,22 @@ describe :file_readable_real, shared: true do
   it "accepts an object that has a #to_path method" do
     File.open(@file,'w') { @object.send(@method, mock_to_path(@file)).should == true }
   end
+
+  platform_is_not :windows do
+    as_real_superuser do
+      context "when run by a real superuser" do
+        it "returns true unconditionally" do
+          file = tmp('temp.txt')
+          touch file
+
+          File.chmod(0333, file)
+          @object.send(@method, file).should == true
+
+          rm_r file
+        end
+      end
+    end
+  end
 end
 
 describe :file_readable_real_missing, shared: true do
diff --git a/spec/ruby/shared/file/writable.rb b/spec/ruby/shared/file/writable.rb
index 4bb8aedce6..65ea2c1781 100644
--- a/spec/ruby/shared/file/writable.rb
+++ b/spec/ruby/shared/file/writable.rb
@@ -19,6 +19,22 @@ describe :file_writable, shared: true do
   it "accepts an object that has a #to_path method" do
     File.open(@file,'w') { @object.send(@method, mock_to_path(@file)).should == true }
   end
+
+  platform_is_not :windows do
+    as_superuser do
+      context "when run by a superuser" do
+        it "returns true unconditionally" do
+          file = tmp('temp.txt')
+          touch file
+
+          File.chmod(0555, file)
+          @object.send(@method, file).should == true
+
+          rm_r file
+        end
+      end
+    end
+  end
 end
 
 describe :file_writable_missing, shared: true do
diff --git a/spec/ruby/shared/file/writable_real.rb b/spec/ruby/shared/file/writable_real.rb
index e9721fd379..b4a0a58c6e 100644
--- a/spec/ruby/shared/file/writable_real.rb
+++ b/spec/ruby/shared/file/writable_real.rb
@@ -24,6 +24,22 @@ describe :file_writable_real, shared: true do
     -> { @object.send(@method, nil)   }.should raise_error(TypeError)
     -> { @object.send(@method, false) }.should raise_error(TypeError)
   end
+
+  platform_is_not :windows do
+    as_real_superuser do
+      context "when run by a real superuser" do
+        it "returns true unconditionally" do
+          file = tmp('temp.txt')
+          touch file
+
+          File.chmod(0555, file)
+          @object.send(@method, file).should == true
+
+          rm_r file
+        end
+      end
+    end
+  end
 end
 
 describe :file_writable_real_missing, shared: true do
diff --git a/spec/ruby/shared/string/end_with.rb b/spec/ruby/shared/string/end_with.rb
index 5f2a011235..0e4c1386e8 100644
--- a/spec/ruby/shared/string/end_with.rb
+++ b/spec/ruby/shared/string/end_with.rb
@@ -38,7 +38,7 @@ describe :end_with, shared: true do
   it "uses only the needed arguments" do
     find = mock('h')
     find.should_not_receive(:to_str)
-    "hello".send(@method).should.end_with?("o",find)
+    "hello".send(@method).should.end_with?("o", find)
   end
 
   it "works for multibyte strings" do
@@ -51,4 +51,11 @@ describe :end_with, shared: true do
       "あれ".send(@method).end_with?(pat)
     end.should raise_error(Encoding::CompatibilityError)
   end
+
+  it "checks that we are starting to match at the head of a character" do
+    "\xC3\xA9".send(@method).should_not.end_with?("\xA9")
+    "\xe3\x81\x82".send(@method).should_not.end_with?("\x82")
+    "ab".force_encoding("UTF-16BE").send(@method).should_not.end_with?(
+        "b".force_encoding("UTF-16BE"))
+  end
 end
diff --git a/spec/ruby/shared/string/start_with.rb b/spec/ruby/shared/string/start_with.rb
index d8d6e13f6a..6932a017b6 100644
--- a/spec/ruby/shared/string/start_with.rb
+++ b/spec/ruby/shared/string/start_with.rb
@@ -69,4 +69,8 @@ describe :start_with, shared: true do
     Regexp.last_match.should be_nil
     $1.should be_nil
   end
+
+  it "does not check that we are not matching part of a character" do
+    "\xC3\xA9".send(@method).should.start_with?("\xC3")
+  end
 end