code: def test_render_message_with_message(self, dag_maker):
      with dag_maker("test_render_message_with_message") as dag:
          EmptyOperator(task_id="test_id")
  
      notifier = MockNotifier(message="Hello {{ dag.dag_id }}")
      context: Context = {"dag": dag}
      notifier.render_template_fields(context)
      assert (
          notifier.message == "Hello test_render_message_with_message"
      )
  
file_path: airflow/tests/notifications/test_basenotifier.py
imports: from __future__ import annotations
  from typing import TYPE_CHECKING
  from unittest.mock import MagicMock
  import jinja2
  import pytest
  from airflow.notifications.basenotifier import BaseNotifier
  from airflow.operators.empty import EmptyOperator
label_desc: Use image node_id 1 for calling the TestBaseNotifier obj's underlying member method code with example usage: obj.test_render_message_with_message(dag_maker) without return types