Add some corner cases to tests for String#index.

* test/ruby/test_string.rb (TestString#test_index): Add some
  corner cases to tests for String#index, which might fail if ruby
  directly used a buggy memmem(3) implementation.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37792 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Thu Nov 22 12:52:19 2012  Akinori MUSHA  <knu@iDaemons.org>
+
+	* test/ruby/test_string.rb (TestString#test_index): Add some
+	  corner cases to tests for String#index, which might fail if ruby
+	  directly used a buggy memmem(3) implementation.
+
 Thu Nov 22 08:06:42 2012  Narihiro Nakamura  <authornari@gmail.com>
 
 	* test/ruby/test_gc.rb (test_profiler_clear): fix wrong method

test/ruby/test_string.rb

@@ -830,6 +830,13 @@ class TestString < Test::Unit::TestCase
     assert_nil(S("hello").index(S("z")))
     assert_nil(S("hello").index(/z./))
 
+    assert_equal(0, S("").index(S("")))
+    assert_equal(0, S("").index(//))
+    assert_nil(S("").index(S("hello")))
+    assert_nil(S("").index(/hello/))
+    assert_equal(0, S("hello").index(S("")))
+    assert_equal(0, S("hello").index(//))
+
     o = Object.new
     def o.to_str; "bar"; end
     assert_equal(3, "foobarbarbaz".index(o))