code: def test_gcp_conn_id(self, get_con_mock):
      gke_op = GKEStartPodOperator(
          project_id=TEST_GCP_PROJECT_ID,
          location=PROJECT_LOCATION,
          cluster_name=CLUSTER_NAME,
          task_id=PROJECT_TASK_ID,
          name=TASK_NAME,
          namespace=NAMESPACE,
          image=IMAGE,
          gcp_conn_id="test_conn",
      )
      gke_op._cluster_url = CLUSTER_URL
      gke_op._ssl_ca_cert = SSL_CA_CERT
      hook = gke_op.hook
  
      assert hook.gcp_conn_id == "test_conn"
  
imports: from __future__ import annotations
  import json
  import os
  from unittest import mock
  import pytest
  from airflow.exceptions import AirflowException, TaskDeferred
  from airflow.models import Connection
  from airflow.providers.cncf.kubernetes.operators.pod import KubernetesPodOperator
  from airflow.providers.cncf.kubernetes.utils.pod_manager import OnFinishAction
  from airflow.providers.google.cloud.operators.kubernetes_engine import GKECreateClusterOperator, GKEDeleteClusterOperator, GKEStartPodOperator
  from airflow.providers.google.cloud.triggers.kubernetes_engine import GKEStartPodTrigger
label_desc: Use image node_id 9 for calling the TestGKEPodOperator obj's underlying member method code with example usage: obj.test_gcp_conn_id(get_con_mock) without return types