def test_strerrorFormatting(self):
        """
        L{_ErrorFormatter.formatError} should use L{os.strerror} to format
        error messages if it is constructed without any better mechanism.
        """
        formatter = _ErrorFormatter(None, None, None)
        message = formatter.formatError(self.probeErrorCode)
        self.assertEqual(message, os.strerror(self.probeErrorCode))

        L{_ErrorFormatter.formatError} should use L{os.strerror} to format
        error messages if it is constructed without any better mechanism.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_strerror.py