def test_expected_services_exist(self, expected_service):
        """
        Tests that the 'user' and 'i18n' services are provided by the Studio runtime.
        """
        descriptor = ItemFactory(category="pure", parent=self.course)
        runtime = _preview_module_system(
            self.request,
            descriptor,
            self.field_data,
        )
        service = runtime.service(descriptor, expected_service)
        self.assertIsNotNone(service)