docstr: Smoke test of ExpertIteration.
docstr_tok: ["Smoke","test","of","ExpertIteration","."]
code: def test_expert_iteration_smoke(self):
      """Smoke test of ExpertIteration."""
      task = rl_task.RLTask("CartPole-v0", max_steps=2)
      tmp_dir = self.create_tempdir().full_path
      agent = training.ExpertIteration(
          task,
          model_fn=self._model_fn,
          optimizer=opt.Adam,
          batch_size=2,
          n_trajectories_per_epoch=2,
          n_train_steps_per_epoch=2,
          n_eval_episodes=1,
          output_dir=tmp_dir,
      )
      agent.run(1)
      self.assertEqual(agent.current_epoch, 1)
  
imports: import functools
  import math
  import os
  import pickle
  from absl.testing import absltest
  import tensorflow
  from trax import layers
  from trax import models
  from trax import optimizers
  from trax import test_utils
  from trax.rl import task
  from trax.rl import training
  from trax.supervised import lr_schedules
label_desc: Use image node_id 3 for calling the TrainingTest obj's underlying member method code with example usage: obj.test_expert_iteration_smoke() without return types