def test_serializeWithClock(self):
        """
        The clock attribute of L{ReconnectingClientFactory} is not serialized,
        and the restored value sets it to the default value, the reactor.
        """
        clock = Clock()
        original = ReconnectingClientFactory()
        original.clock = clock
        reconstituted = pickle.loads(pickle.dumps(original))
        self.assertIsNone(reconstituted.clock)

        The clock attribute of L{ReconnectingClientFactory} is not serialized,
        and the restored value sets it to the default value, the reactor.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_factories.py