Issue #7849: Now the utility ``check_warnings`` verifies if the warnings are
effectively raised.  A new utility ``check_py3k_warnings`` deals with py3k warnings.
diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 5eb331a..a859c0f 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -512,8 +512,7 @@
         )
 
         if not sys.platform.startswith('java'):
-            # Silence Py3k warning
-            with test_support.check_warnings():
+            with test_support.check_py3k_warnings():
                 buf = buffer('character buffers are decoded to unicode')
             self.assertEqual(
                 unicode(