code: def testSparseClusterSpecRead(self):
      os.environ[
          "TF_CONFIG"
      ] = """
      {
        "cluster": {
          "ps": ["ps0:2222", "ps1:2222"],
          "worker": {"1": "worker1:2222"}
        },
        "task": {
          "type": "worker",
          "index": 1
        }
      }
      """
  
      cluster_resolver = (
          tfconfig_cluster_resolver.TFConfigClusterResolver()
      )
      expected_proto = """
      job { name: 'ps' tasks { key: 0 value: 'ps0:2222' }
                       tasks { key: 1 value: 'ps1:2222' } }
      job { name: 'worker' tasks { key: 1 value: 'worker1:2222' } }
      """
      actual_cluster_spec = cluster_resolver.cluster_spec()
      self._verifyClusterSpecEquality(
          actual_cluster_spec, expected_proto
      )
  
imports: import os
  from tensorflow.python.client import session
  from tensorflow.python.distribute.cluster_resolver import tfconfig_cluster_resolver
  from tensorflow.python.eager import context
  from tensorflow.python.framework import config
  from tensorflow.python.framework import test_util
  from tensorflow.python.platform import test
  from tensorflow.python.training import server_lib
label_desc: Use image node_id 3 for calling the TFConfigClusterResolverTest obj's underlying member method code with example usage: obj.testSparseClusterSpecRead() without return types