Fixed #14508 - test suite silences warnings.

Utility functions get_warnings_state and save_warnings_state have been added
to django.test.utils, and methods to django.test.TestCase for convenience.

The implementation is based on the catch_warnings context manager from
Python 2.6.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14526 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/regressiontests/csrf_tests/tests.py

@@ -71,12 +71,12 @@ class CsrfMiddlewareTest(TestCase):
     _secret_key_for_session_test= "test"
 
     def setUp(self):
+        self.save_warnings_state()
         warnings.filterwarnings('ignore', category=DeprecationWarning,
                                 module='django.middleware.csrf')
 
     def tearDown(self):
-        warnings.resetwarnings()
-        warnings.simplefilter('ignore', PendingDeprecationWarning)
+        self.restore_warnings_state()
 
     def _get_GET_no_csrf_cookie_request(self):
         return TestingHttpRequest()