1 files changed, 153 insertions, 31 deletions

diff --git a/spec/ruby/core/string/downcase_spec.rb b/spec/ruby/core/string/downcase_spec.rb
index f591c0fa09..4f7f44e5d4 100644
--- a/spec/ruby/core/string/downcase_spec.rb
+++ b/spec/ruby/core/string/downcase_spec.rb
@@ -1,6 +1,7 @@
 # -*- encoding: utf-8 -*-
-require File.expand_path('../../../spec_helper', __FILE__)
-require File.expand_path('../fixtures/classes.rb', __FILE__)
+# frozen_string_literal: false
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
 describe "String#downcase" do
   it "returns a copy of self with all uppercase letters downcased" do
@@ -8,50 +9,173 @@ describe "String#downcase" do
     "hello".downcase.should == "hello"
   end
 
-  ruby_version_is ''...'2.4' do
-    it "is locale insensitive (only replaces A-Z)" do
-      "ÄÖÜ".downcase.should == "ÄÖÜ"
+  it "returns a String in the same encoding as self" do
+    "hELLO".encode("US-ASCII").downcase.encoding.should == Encoding::US_ASCII
+  end
+
+  describe "full Unicode case mapping" do
+    it "works for all of Unicode with no option" do
+      "ÄÖÜ".downcase.should == "äöü"
+    end
 
-      str = Array.new(256) { |c| c.chr }.join
-      expected = Array.new(256) do |i|
-        c = i.chr
-        c.between?("A", "Z") ? c.downcase : c
-      end.join
+    it "updates string metadata" do
+      downcased = "\u{212A}ING".downcase
 
-      str.downcase.should == expected
+      downcased.should == "king"
+      downcased.size.should == 4
+      downcased.bytesize.should == 4
+      downcased.ascii_only?.should == true
     end
   end
 
-  ruby_version_is '2.4' do
-    it "works for all of Unicode" do
-      "ÄÖÜ".downcase.should == "äöü"
+  describe "ASCII-only case mapping" 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
+    it "downcases characters according to Turkic semantics" do
+      "İ".downcase(:turkic).should == "i"
+    end
+
+    it "allows Lithuanian as an extra option" do
+      "İ".downcase(:turkic, :lithuanian).should == "i"
+    end
+
+    it "does not allow any other additional option" do
+      -> { "İ".downcase(:turkic, :ascii) }.should.raise(ArgumentError)
     end
   end
 
-  it "taints result when self is tainted" do
-    "".taint.downcase.tainted?.should == true
-    "x".taint.downcase.tainted?.should == true
-    "X".taint.downcase.tainted?.should == true
+  describe "full Unicode case mapping adapted for Lithuanian" do
+    it "currently works the same as full Unicode case mapping" do
+      "İS".downcase(:lithuanian).should == "i\u{307}s"
+    end
+
+    it "allows Turkic as an extra option (and applies Turkic semantics)" do
+      "İS".downcase(:lithuanian, :turkic).should == "is"
+    end
+
+    it "does not allow any other additional option" do
+      -> { "İS".downcase(:lithuanian, :ascii) }.should.raise(ArgumentError)
+    end
+  end
+
+  describe "case folding" do
+    it "case folds special characters" do
+      "ß".downcase.should == "ß"
+      "ß".downcase(:fold).should == "ss"
+    end
+  end
+
+  it "does not allow invalid options" do
+    -> { "ABC".downcase(:invalid_option) }.should.raise(ArgumentError)
   end
 
-  it "returns a subclass instance for subclasses" do
-    StringSpecs::MyString.new("FOObar").downcase.should be_an_instance_of(StringSpecs::MyString)
+  it "returns a String instance for subclasses" do
+    StringSpecs::MyString.new("FOObar").downcase.should.instance_of?(String)
   end
 end
 
 describe "String#downcase!" do
   it "modifies self in place" do
     a = "HeLlO"
-    a.downcase!.should equal(a)
+    a.downcase!.should.equal?(a)
     a.should == "hello"
   end
 
-  ruby_version_is '2.4' do
-    it "modifies self in place for all of Unicode" do
+  it "modifies self in place for non-ascii-compatible encodings" do
+    a = "HeLlO".encode("utf-16le")
+    a.downcase!
+    a.should == "hello".encode("utf-16le")
+  end
+
+  describe "full Unicode case mapping" do
+    it "modifies self in place for all of Unicode with no option" do
       a = "ÄÖÜ"
-      a.downcase!.should equal(a)
+      a.downcase!
       a.should == "äöü"
     end
+
+    it "updates string metadata" do
+      downcased = "\u{212A}ING"
+      downcased.downcase!
+
+      downcased.should == "king"
+      downcased.size.should == 4
+      downcased.bytesize.should == 4
+      downcased.ascii_only?.should == true
+    end
+  end
+
+  describe "ASCII-only case mapping" do
+    it "does not downcase non-ASCII characters" do
+      a = "CÅR"
+      a.downcase!(:ascii)
+      a.should == "cÅr"
+    end
+
+    it "works for non-ascii-compatible encodings" do
+      a = "ABC".encode("utf-16le")
+      a.downcase!(:ascii)
+      a.should == "abc".encode("utf-16le")
+    end
+  end
+
+  describe "full Unicode case mapping adapted for Turkic languages" do
+    it "downcases characters according to Turkic semantics" do
+      a = "İ"
+      a.downcase!(:turkic)
+      a.should == "i"
+    end
+
+    it "allows Lithuanian as an extra option" do
+      a = "İ"
+      a.downcase!(:turkic, :lithuanian)
+      a.should == "i"
+    end
+
+    it "does not allow any other additional option" do
+      -> { a = "İ"; a.downcase!(:turkic, :ascii) }.should.raise(ArgumentError)
+    end
+  end
+
+  describe "full Unicode case mapping adapted for Lithuanian" do
+    it "currently works the same as full Unicode case mapping" do
+      a = "İS"
+      a.downcase!(:lithuanian)
+      a.should == "i\u{307}s"
+    end
+
+    it "allows Turkic as an extra option (and applies Turkic semantics)" do
+      a = "İS"
+      a.downcase!(:lithuanian, :turkic)
+      a.should == "is"
+    end
+
+    it "does not allow any other additional option" do
+      -> { a = "İS"; a.downcase!(:lithuanian, :ascii) }.should.raise(ArgumentError)
+    end
+  end
+
+  describe "case folding" do
+    it "case folds special characters" do
+      a = "ß"
+      a.downcase!
+      a.should == "ß"
+
+      a.downcase!(:fold)
+      a.should == "ss"
+    end
+  end
+
+  it "does not allow invalid options" do
+    -> { a = "ABC"; a.downcase!(:invalid_option) }.should.raise(ArgumentError)
   end
 
   it "returns nil if no modifications were made" do
@@ -60,14 +184,12 @@ describe "String#downcase!" do
     a.should == "hello"
   end
 
-  it "raises a RuntimeError when self is frozen" do
-    lambda { "HeLlo".freeze.downcase! }.should raise_error(RuntimeError)
-    lambda { "hello".freeze.downcase! }.should raise_error(RuntimeError)
+  it "raises a FrozenError when self is frozen" do
+    -> { "HeLlo".freeze.downcase! }.should.raise(FrozenError)
+    -> { "hello".freeze.downcase! }.should.raise(FrozenError)
   end
 
-  with_feature :encoding do
-    it "sets the result String encoding to the source String encoding" do
-      "ABC".downcase.encoding.should equal(Encoding::UTF_8)
-    end
+  it "sets the result String encoding to the source String encoding" do
+    "ABC".downcase.encoding.should.equal?(Encoding::UTF_8)
   end
 end