Following OpenStack Style Guidelines[1]: http://docs.openstack.org/developer/hacking/#unit-tests-and-assertraises [H203] 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: I52ecf3f4945c4cb99f6350afca1c51d88b16bb8d