def test_mainClassNotFound(self):
        """
        Will raise an exception when called with an argument which is a
        dotted patch which can not be imported..
        """
        exception = self.assertRaises(
            ValueError,
            stdio.main, argv=['no-such-class'],
            )

        self.assertEqual('Empty module name', exception.args[0])

        Will raise an exception when called with an argument which is a
        dotted patch which can not be imported..
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_manhole.py