class_docstr: Tests for policy loader.
class_docstr_tok: ["Tests","for","policy","loader","."]
code: def testMaterialize(self):
      saved_path, ckpt_at_path_1 = self._createModelsOnDisk()
      materialized_path = os.path.join(self.root_dir, "material/001")
      policy_loader.materialize_saved_model(
          saved_path, ckpt_at_path_1, materialized_path
      )
      policy_at_1 = policy_loader.load(materialized_path)
      self.assertEqual(1, policy_at_1.get_train_step())
      self.assertEqual(10, policy_at_1.variables()[0].numpy())
  
imports: import os
  import numpy
  import tensorflow.compat.v2
  from tf_agents.networks import network
  from tf_agents.policies import greedy_policy
  from tf_agents.policies import policy_loader
  from tf_agents.policies import policy_saver
  from tf_agents.policies import q_policy
  from tf_agents.specs import tensor_spec
  from tf_agents.trajectories import time_step
  from tf_agents.utils import common
  from tf_agents.utils import test_utils
label_desc: Use image node_id 4 for calling the PolicyLoaderTest obj's underlying member method code with example usage: obj.testMaterialize() without return types