def test_formatUnformattableEvent(self):
        """
        Formatting an event that's just plain out to get us.
        """
        event = dict(log_format="{evil()}", evil=lambda: 1 / 0)
        result = formatEvent(event)

        self.assertIn("Unable to format event", result)
        self.assertIn(repr(event), result)

        Formatting an event that's just plain out to get us.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/logger/test/test_format.py