def test_displaysListCorrectly(self):
        """
        The C{--help-auth} argument correctly displays all
        available authentication plugins, then exits.
        """
        newStdout = NativeStringIO()
        options = DummyOptions()
        options.authOutput = newStdout
        self.assertRaises(SystemExit, options.parseOptions, ['--help-auth'])
        for checkerFactory in strcred.findCheckerFactories():
            self.assertIn(checkerFactory.authType, newStdout.getvalue())

        The C{--help-auth} argument correctly displays all
        available authentication plugins, then exits.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/cred/test/test_strcred.py