code: def testOneItemInClusterSpecMasterRead(self):
      os.environ["SM_HOSTS"] = '["algo-1"]'
      os.environ["SM_CURRENT_HOST"] = ""
  
      cluster_resolver = SageMakerClusterResolver()
      self.assertEqual("", cluster_resolver.master())
  
file_path: tensorflow/tensorflow/python/distribute/cluster_resolver/sagemaker_cluster_resolver_test.py
imports: import os
  from tensorflow.python.distribute.cluster_resolver.sagemaker_cluster_resolver import SageMakerClusterResolver
  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 9 for calling the SageMakerClusterResolverTest obj's underlying member method code with example usage: obj.testOneItemInClusterSpecMasterRead() without return types