def test_formatSystemRulz(self):
        """
        System is not supplanted by namespace and level.
        """
        event = dict(
            log_format=u"XYZZY",
            log_namespace="my.namespace",
            log_level=LogLevel.warn,
            log_system=u"S.Y.S.T.E.M.",
        )
        self.assertEqual(
            formatEventAsClassicLogText(event),
            u"- [S.Y.S.T.E.M.] XYZZY\n",
        )

        System is not supplanted by namespace and level.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/logger/test/test_format.py