test/uri/test_generic.rb (to_s): new test

Ensure URI::Generic#to_s continues to return mutable strings to
prevent breakage when we enable frozen string literals in future
commits.

[ruby-core:71820]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52980 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Wed Dec  9 06:25:47 2015  Eric Wong  <e@80x24.org>
+
+	* test/uri/test_generic.rb (to_s): new test
+	  [ruby-core:71820]
+
 Wed Dec  9 02:18:52 2015  Koichi Sasada  <ko1@atdot.net>
 
 	* compile.c (ibf_dump_memsize): should check NULL.

test/uri/test_generic.rb

@@ -14,6 +14,13 @@ class URI::TestGeneric < Test::Unit::TestCase
     uri.class.component.collect {|c| uri.send(c)}
   end
 
+  def test_to_s
+    exp = 'http://example.com/'.freeze
+    str = URI(exp).to_s
+    assert_equal exp, str
+    refute_predicate str, :frozen?, '[ruby-core:71785] [Bug #11759]'
+  end
+
   def test_parse
     # 0
     assert_kind_of(URI::HTTP, @base_url)