
Refer to:http://docs.openstack.org/developer/hacking/#unit-tests-and-assertraises [H203] Use assertIs(Not)None to check for None (off by default) Unit test assertions tend to give better messages for more specific assertions. As a result, assertIsNone(...) is preferred over assertEqual(None, ...) and assertIs(None, ...) Change-Id: I4e60f3f7f3557080669b98cb48627acc40a72606