def test_descendantOnly(self):
        """
        If C{".."} is in the sequence passed to L{FilePath.descendant},
        L{InsecurePath} is raised.
        """
        self.assertRaises(
            filepath.InsecurePath,
            self.path.descendant, [u'mon\u20acy', u'..'])

        If C{".."} is in the sequence passed to L{FilePath.descendant},
        L{InsecurePath} is raised.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_paths.py