def test_winError(self):
        """
        L{_ErrorFormatter.formatError} should return the message argument from
        the exception L{winError} returns, if L{winError} is supplied.
        """
        winCalls = []
        def winError(errorCode):
            winCalls.append(errorCode)
            return _MyWindowsException(errorCode, self.probeMessage)
        formatter = _ErrorFormatter(
            winError,
            lambda error: 'formatMessage: wrong message',
            {self.probeErrorCode: 'errorTab: wrong message'})
        message = formatter.formatError(self.probeErrorCode)
        self.assertEqual(message, self.probeMessage)

        L{_ErrorFormatter.formatError} should return the message argument from
        the exception L{winError} returns, if L{winError} is supplied.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_strerror.py