code: def testRetrieveProjectAndZoneFromMetadataNoCoordinator(self):
      tpu_map = {
          "projects/test-project/locations/us-central1-c/nodes/test-tpu-1": {
              "ipAddress": "10.1.2.3",
              "port": "8470",
              "state": "READY",
              "health": "HEALTHY",
          }
      }
  
      cluster_resolver = resolver.TPUClusterResolver(
          project=None,
          zone=None,
          tpu=["test-tpu-1"],
          coordinator_name=None,
          credentials=None,
          service=self.mock_service_client(tpu_map=tpu_map),
      )
  
      actual_cluster_spec = cluster_resolver.cluster_spec()
      expected_proto = """
      job { name: 'worker' tasks { key: 0 value: '10.1.2.3:8470' } }
      """
      self._verifyClusterSpecEquality(
          actual_cluster_spec, expected_proto
      )
      self.assertEqual(
          cluster_resolver.master(), "grpc://10.1.2.3:8470"
      )
  
imports: import os
  import six
  from six.moves.urllib.error import URLError
  from tensorflow.core.protobuf.tpu import topology_pb2
  from tensorflow.python.client import session
  from tensorflow.python.distribute.cluster_resolver.tpu import tpu_cluster_resolver
  from tensorflow.python.eager import context
  from tensorflow.python.framework import config
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import test_util
  from tensorflow.python.platform import test
  from tensorflow.python.platform import tf_logging
  from tensorflow.python.training import server_lib
  from tensorflow.python.util import compat
label_desc: Use image node_id 6 for calling the TPUClusterResolverTest obj's underlying member method code with example usage: obj.testRetrieveProjectAndZoneFromMetadataNoCoordinator() without return types