implement String/Symbol#casecmp? including Unicode case folding

* string.c: Implement String#casecmp? and Symbol#casecmp? by using
  String#downcase :fold for Unicode case folding. This does not include
  options such as :turkic, because these currently cannot be combined
  with the :fold option. This implements feature #12786.

* test/ruby/test_string.rb/test_symbol.rb: Tests for above.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56912 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 7 insertions, 0 deletions

diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index b1d795e183..90f48e4f08 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -2210,6 +2210,13 @@ CODE
     assert_equal(1, "\u3042B".casecmp("\u3042a"))
   end
 
+  def test_casecmp?
+    assert_equal(true, 'FoO'.casecmp?('fOO'))
+    assert_equal(false, 'FoO'.casecmp?('BaR'))
+    assert_equal(false, 'baR'.casecmp?('FoO'))
+    assert_equal(true, 'äöü'.casecmp?('ÄÖÜ'))
+  end
+
   def test_upcase2
     assert_equal("\u3042AB", "\u3042aB".upcase)
   end