def test_message(self):
        """
        The old-style C{"message"} key is added, even if no new-style
        C{"log_format"} is given, as it is required, but may be empty.
        """
        event = self.forwardAndVerify(dict())
        self.assertEqual(event["message"], ())  # "message" is a tuple

        The old-style C{"message"} key is added, even if no new-style
        C{"log_format"} is given, as it is required, but may be empty.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/logger/test/test_legacy.py