def test_readOnlySavePath(self):
        """
        L{KnownHostsFile.savePath} is read-only; if an assignment is made to
        it, L{AttributeError} is raised and the value is unchanged.
        """
        path = FilePath(self.mktemp())
        new = FilePath(self.mktemp())
        hostsFile = KnownHostsFile(path)
        self.assertRaises(AttributeError, setattr, hostsFile, "savePath", new)
        self.assertEqual(path, hostsFile.savePath)

        L{KnownHostsFile.savePath} is read-only; if an assignment is made to
        it, L{AttributeError} is raised and the value is unchanged.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_knownhosts.py