def METHOD_NAME(self):
    ps_cs_setting = self.test_app.settings_set.select_subclasses().get(
        name="primary"
    )
    ps_cs_setting.persistent_store_service = None
    ps_cs_setting.save()
    # Check ValidationError
    self.assertRaises(
        ValidationError,
        PersistentStoreConnectionSetting.objects.get(name="primary").clean,
    )