def test_failuresAppendTracebacks(self):
        """
        The string resulting from a logged failure contains a traceback.
        """
        f = Failure(Exception("this is not the behavior you are looking for"))
        log = Logger(observer=self.publisher)
        log.failure('a failure', failure=f)
        msg = self.errorStream.getvalue()
        self.assertIn('a failure', msg)
        self.assertIn('this is not the behavior you are looking for', msg)
        self.assertIn('Traceback', msg)

        The string resulting from a logged failure contains a traceback.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/logger/test/test_global.py