code: def test_gpu_env(self):
      ret = parl.utils.machine_info.is_gpu_available()
      assert ret == self.return_value
  
imports: from parl.remote.test_utils import MockingEnv
  from parl.remote.test_utils import env_config_for_test
  import unittest
  import parl
label_desc: Use image node_id 1 for calling the TestMockingEnv obj's underlying member method code with example usage: obj.test_gpu_env() without return types