Make return value from bang methods match Ruby docs

The docs for the String class indicate that methods like `rstrip!` and
others should return nil when they do not have an effect on the string.

1 files changed, 10 insertions, 4 deletions

diff --git a/activesupport/test/multibyte_chars_test.rb b/activesupport/test/multibyte_chars_test.rb
index 006e5c5927..41248cccb6 100644
--- a/activesupport/test/multibyte_chars_test.rb
+++ b/activesupport/test/multibyte_chars_test.rb
@@ -7,6 +7,7 @@ class String
   def __method_for_multibyte_testing_with_integer_result; 1; end
   def __method_for_multibyte_testing; 'result'; end
   def __method_for_multibyte_testing!; 'result'; end
+  def __method_for_multibyte_testing_that_returns_nil!; end
 end
 
 class MultibyteCharsTest < Test::Unit::TestCase
@@ -36,11 +37,15 @@ class MultibyteCharsTest < Test::Unit::TestCase
     assert_not_equal @chars.object_id, @chars.__method_for_multibyte_testing.object_id
   end
 
-  def test_forwarded_bang_method_calls_should_return_the_original_chars_instance
+  def test_forwarded_bang_method_calls_should_return_the_original_chars_instance_when_result_is_not_nil
     assert_kind_of @proxy_class, @chars.__method_for_multibyte_testing!
     assert_equal @chars.object_id, @chars.__method_for_multibyte_testing!.object_id
   end
 
+  def test_forwarded_bang_method_calls_should_return_nil_when_result_is_nil
+    assert_nil @chars.__method_for_multibyte_testing_that_returns_nil!
+  end
+
   def test_methods_are_forwarded_to_wrapped_string_for_byte_strings
     assert_equal BYTE_STRING.class, BYTE_STRING.mb_chars.class
   end
@@ -117,10 +122,11 @@ class MultibyteCharsUTF8BehaviourTest < Test::Unit::TestCase
     assert_equal 'こに わ', @chars
   end
 
-  %w{capitalize downcase lstrip reverse rstrip strip upcase}.each do |method|
+  %w{capitalize downcase lstrip reverse rstrip upcase}.each do |method|
     class_eval(<<-EOTESTS)
-      def test_#{method}_bang_should_return_self
-        assert_equal @chars.object_id, @chars.send("#{method}!").object_id
+      def test_#{method}_bang_should_return_self_when_modifying_wrapped_string
+        chars = ' él piDió Un bUen café '
+        assert_equal chars.object_id, chars.send("#{method}!").object_id
       end
 
       def test_#{method}_bang_should_change_wrapped_string