code: def test_start(self):
      celery_executor_mock = mock.MagicMock()
      k8s_executor_mock = mock.MagicMock()
      cke = CeleryKubernetesExecutor(
          celery_executor_mock, k8s_executor_mock
      )
  
      cke.start()
  
      celery_executor_mock.start.assert_called()
      k8s_executor_mock.start.assert_called()
  
imports: from __future__ import annotations
  from unittest import mock
  import pytest
  from airflow.callbacks.callback_requests import CallbackRequest
  from airflow.configuration import conf
  from airflow.providers.celery.executors.celery_executor import CeleryExecutor
  from airflow.providers.celery.executors.celery_kubernetes_executor import CeleryKubernetesExecutor
  from airflow.providers.cncf.kubernetes.executors.kubernetes_executor import KubernetesExecutor
label_desc: Use image node_id 10 for calling the TestCeleryKubernetesExecutor obj's underlying member method code with example usage: obj.test_start() without return types