def test_noKeysForUnauthorizedUser(self):
        """
        If the user is not in the user database provided to
        L{checkers.UNIXAuthorizedKeysFiles}, an empty iterator is returned
        by L{checkers.UNIXAuthorizedKeysFiles.getAuthorizedKeys}.
        """
        keydb = checkers.UNIXAuthorizedKeysFiles(self.userdb,
                                                 parseKey=lambda x: x)
        self.assertEqual([], list(keydb.getAuthorizedKeys('bob')))

        If the user is not in the user database provided to
        L{checkers.UNIXAuthorizedKeysFiles}, an empty iterator is returned
        by L{checkers.UNIXAuthorizedKeysFiles.getAuthorizedKeys}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_checkers.py