code: def test_round_robin_mock(self):
      env = RoundRobinMultiAgent(2)
      obs, info = env.reset()
      self.assertEqual(obs, {0: 0})
      for _ in range(5):
          obs, rew, done, truncated, info = env.step({0: 0})
          self.assertEqual(obs, {1: 0})
          self.assertEqual(done["__all__"], False)
          obs, rew, done, truncated, info = env.step({1: 0})
          self.assertEqual(obs, {0: 0})
          self.assertEqual(done["__all__"], False)
      obs, rew, done, truncated, info = env.step({0: 0})
      self.assertEqual(done["__all__"], True)
  
imports: import gymnasium
  import numpy
  import random
  import tree
  import unittest
  import ray
  from ray.tune.registry import register_env
  from ray.rllib.algorithms.algorithm_config import AlgorithmConfig
  from ray.rllib.algorithms.dqn.dqn import DQNConfig
  from ray.rllib.algorithms.dqn.dqn_tf_policy import DQNTFPolicy
  from ray.rllib.algorithms.ppo import PPOConfig
  from ray.rllib.env.multi_agent_env import make_multi_agent, MultiAgentEnvWrapper
  from ray.rllib.evaluation.episode import Episode
  from ray.rllib.evaluation.rollout_worker import get_global_worker, RolloutWorker
  from ray.rllib.evaluation.tests.test_rollout_worker import MockPolicy
  from ray.rllib.examples.policy.random_policy import RandomPolicy
  from ray.rllib.examples.env.multi_agent import MultiAgentCartPole, BasicMultiAgent, EarlyDoneMultiAgent, FlexAgentsMultiAgent, RoundRobinMultiAgent, SometimesZeroAgentsMultiAgent
  from ray.rllib.policy.policy import PolicySpec
  from ray.rllib.policy.sample_batch import convert_ma_batch_to_sample_batch
  from ray.rllib.tests.test_nested_observation_spaces import NestedMultiAgentEnv
  from ray.rllib.utils.numpy import one_hot
  from ray.rllib.utils.test_utils import check
label_desc: Use image node_id 4 for calling the TestMultiAgentEnv obj's underlying member method code with example usage: obj.test_round_robin_mock() without return types