def test_displaysHelpCorrectly(self):
        """
        The C{--help-auth-for} argument will correctly display the help file for a
        particular authentication plugin.
        """
        newStdout = NativeStringIO()
        options = DummyOptions()
        options.authOutput = newStdout
        self.assertRaises(
            SystemExit, options.parseOptions, ['--help-auth-type', 'file'])
        for line in cred_file.theFileCheckerFactory.authHelp:
            if line.strip():
                self.assertIn(line.strip(), newStdout.getvalue())

        The C{--help-auth-for} argument will correctly display the help file for a
        particular authentication plugin.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/cred/test/test_strcred.py