3 files changed, 5 insertions, 6 deletions
diff --git a/activesupport/test/core_ext/duration_test.rb b/activesupport/test/core_ext/duration_test.rb
index 05f529dc7d..710c221fac 100644
--- a/activesupport/test/core_ext/duration_test.rb
+++ b/activesupport/test/core_ext/duration_test.rb
@@ -5,6 +5,7 @@ class DurationTest < ActiveSupport::TestCase
   def test_is_a
     d = 1.day
     assert d.is_a?(ActiveSupport::Duration)
+    assert_kind_of ActiveSupport::Duration, d
     assert_kind_of Numeric, d
     assert_kind_of Fixnum, d
     assert !d.is_a?(Hash)
diff --git a/activesupport/test/core_ext/string_ext_test.rb b/activesupport/test/core_ext/string_ext_test.rb
index ea21e445e2..759b0ddcd6 100644
--- a/activesupport/test/core_ext/string_ext_test.rb
+++ b/activesupport/test/core_ext/string_ext_test.rb
@@ -245,11 +245,9 @@ class CoreExtStringMultibyteTest < ActiveSupport::TestCase
         assert_kind_of ActiveSupport::Multibyte.proxy_class, UNICODE_STRING.mb_chars
       end
     end
-  end
-
-  if RUBY_VERSION >= '1.9'
-    def test_mb_chars_returns_string
-      assert_kind_of String, UNICODE_STRING.mb_chars
+  else
+    def test_mb_chars_returns_instance_of_proxy_class
+      assert_kind_of ActiveSupport::Multibyte.proxy_class, UNICODE_STRING.mb_chars
     end
   end
 end
diff --git a/activesupport/test/core_ext/time_with_zone_test.rb b/activesupport/test/core_ext/time_with_zone_test.rb
index 77b1893f77..2cf5bd6ea9 100644
--- a/activesupport/test/core_ext/time_with_zone_test.rb
+++ b/activesupport/test/core_ext/time_with_zone_test.rb
@@ -326,7 +326,7 @@ class TimeWithZoneTest < Test::Unit::TestCase
   def test_is_a
     assert_kind_of Time, @twz
     assert_kind_of Time, @twz
-    assert ActiveSupport::TimeWithZone, @twz
+    assert_kind_of ActiveSupport::TimeWithZone, @twz
   end
   
   def test_class_name