code: def testSavingFrames(self):
      self._decorator.reset()
      self._decorator.step(None, 1)
      self._decorator.step(None, 1)
  
      temp_dir = tempfile.mkdtemp()
      self._decorator.save_frames(temp_dir)
  
      for index, observation in enumerate(self._env.test_observations):
          expected_image = observation["RGB_INTERLEAVED"]
          image_file_name = os.path.join(
              temp_dir, "frame{0}.png".format(index)
          )
          image = np.asarray(Image.open(image_file_name))
          self.assertTrue(np.array_equal(image, expected_image))
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  import tempfile
  from absl.testing import absltest
  import numpy
  import six
  from PIL import Image
  from python.tests.utils import test_environment_decorator
label_desc: Use image node_id 13 for calling the TestEnvironmentDecoratorTest obj's underlying member method code with example usage: obj.testSavingFrames() without return types