code: def test_pixel_env_invalid_environment_type(self):
      with pytest.raises(ValueError):
          self.env.observation_space = gym.spaces.Discrete(64)
          PixelObservationWrapper(self.env)
  
file_path: garage/tests/garage/envs/wrappers/test_pixel_observation_wrapper.py
imports: import gym
  import numpy
  import pytest
  from garage.envs.wrappers import PixelObservationWrapper
label_desc: Use image node_id 3 for calling the TestPixelObservationWrapper obj's underlying member method code with example usage: obj.test_pixel_env_invalid_environment_type() without return types