text: import pytest
  import io
  import os
  from unittest.mock import patch
  
  from mlagents.trainers import trainer_util
  from mlagents.trainers.cli_utils import load_config, _load_config
  from mlagents.trainers.ppo.trainer import PPOTrainer
  from mlagents.trainers.exception import TrainerConfigError, UnityTrainerException
  from mlagents.trainers.settings import RunOptions
  from mlagents.trainers.tests.test_simple_rl import PPO_CONFIG
  
  
  @pytest.fixture
  def dummy_config():
      return RunOptions(behaviors={"testbrain": PPO_CONFIG})
  
  
  @patch("mlagents_envs.base_env.BehaviorSpec")
  def test_initialize_ppo_trainer(BehaviorSpecMock, dummy_config):
      brain_name = "testbrain"
      training_behaviors = {"testbrain": BehaviorSpecMock()}
      output_path = "results_dir"
      train_model = True
      load_model = False
      seed = 11
      expected_reward_buff_cap = 1
  
      base_config = dummy_config.behaviors
      expected_config = PPO_CONFIG
  
      def mock_constructor(
          self,
          brain,
          reward_buff_cap,
          trainer_settings,
          training,
          load,
          seed,
          artifact_path,
      ):
          assert brain == brain_name
          assert trainer_settings == expected_config
          assert reward_buff_cap == expected_reward_buff_cap
          assert training == train_model
          assert load == load_model
          assert seed == seed
          assert artifact_path == os.path.join(output_path, brain_name)
  
      with patch.object(PPOTrainer, "__init__", mock_constructor):
          trainer_factory = trainer_util.TrainerFactory(
              trainer_config=base_config,
              output_path=output_path,
              train_model=train_model,
              load_model=load_model,
              seed=seed,
          )
          trainers = {}
          for brain_name in training_behaviors.keys():
              trainers[brain_name] = trainer_factory.generate(brain_name)
          assert "testbrain" in trainers
          assert isinstance(trainers["testbrain"], PPOTrainer)
  
  
  def test_handles_no_config_provided():
      """
      Make sure the trainer setup handles no configs provided at all.
      """
      brain_name = "testbrain"
      no_default_config = RunOptions().behaviors
  
      trainer_factory = trainer_util.TrainerFactory(
          trainer_config=no_default_config,
          output_path="output_path",
          train_model=True,
          load_model=False,
          seed=42,
      )
      trainer_factory.generate(brain_name)
  
  
  def test_load_config_missing_file():
      with pytest.raises(TrainerConfigError):
          load_config("thisFileDefinitelyDoesNotExist.yaml")
  
  
  def test_load_config_valid_yaml():
      file_contents = """
  this:
    - is fine
      """
      fp = io.StringIO(file_contents)
      res = _load_config(fp)
      assert res == {"this": ["is fine"]}
  
  
  def test_load_config_invalid_yaml():
      file_contents = """
  you:
    - will
  - not
    - parse
      """
      with pytest.raises(TrainerConfigError):
          fp = io.StringIO(file_contents)
          _load_config(fp)
  
  
  def test_existing_directories(tmp_path):
      output_path = os.path.join(tmp_path, "runid")
      # Test fresh new unused path - should do nothing.
      trainer_util.handle_existing_directories(output_path, False, False)
      # Test resume with fresh path - should throw an exception.
      with pytest.raises(UnityTrainerException):
          trainer_util.handle_existing_directories(output_path, True, False)
  
      # make a directory
      os.mkdir(output_path)
      # Test try to train w.o. force, should complain
      with pytest.raises(UnityTrainerException):
          trainer_util.handle_existing_directories(output_path, False, False)
      # Test try to train w/ resume - should work
      trainer_util.handle_existing_directories(output_path, True, False)
      # Test try to train w/ force - should work
      trainer_util.handle_existing_directories(output_path, False, True)
  
      # Test initialize option
      init_path = os.path.join(tmp_path, "runid2")
      with pytest.raises(UnityTrainerException):
          trainer_util.handle_existing_directories(output_path, False, True, init_path)
      os.mkdir(init_path)
      # Should pass since the directory exists now.
      trainer_util.handle_existing_directories(output_path, False, True, init_path)
  