def test_ignoresUnreadableFile(self):
        """
        L{checkers.UNIXAuthorizedKeysFiles.getAuthorizedKeys} returns only
        the keys in C{~/.ssh/authorized_keys} and C{~/.ssh/authorized_keys2}
        if they are readable.
        """
        self.sshDir.child('authorized_keys2').makedirs()
        keydb = checkers.UNIXAuthorizedKeysFiles(self.userdb,
                                                 parseKey=lambda x: x)
        self.assertEqual(self.expectedKeys,
                         list(keydb.getAuthorizedKeys(b'alice')))

        L{checkers.UNIXAuthorizedKeysFiles.getAuthorizedKeys} returns only
        the keys in C{~/.ssh/authorized_keys} and C{~/.ssh/authorized_keys2}
        if they are readable.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_checkers.py