def test_getUserNonexistentDatabase(self):
        """
        A missing db file will cause a permanent rejection of authorization
        attempts.
        """
        self.db = checkers.FilePasswordDB('test_thisbetternoteverexist.db')

        self.assertRaises(error.UnauthorizedLogin, self.db.getUser, 'user')

        A missing db file will cause a permanent rejection of authorization
        attempts.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/cred/test/test_cred.py