def METHOD_NAME(self):
    with mock.patch("certbot.plugins.storage.logger.error") as mock_log:
        # Set data as something that can't be serialized
        self.plugin.storage._initialized = True  # pylint: disable=protected-access
        self.plugin.storage._storagepath = "/tmp/whatever"
        self.plugin.storage._data = self.plugin_cls  # pylint: disable=protected-access
        with pytest.raises(errors.PluginStorageError):
            self.plugin.storage.save()
        assert "Could not serialize" in mock_log.call_args[0][0]