code: def test_get_variables(self, mock_learner):
      learner = frozen_learner.FrozenLearner(mock_learner)
  
      mock_learner.get_variables.return_value = [1, 2]
  
      variables = learner.get_variables(["a", "b"])
      # Values should match with those returned by the wrapped learner.
      self.assertEqual(variables, [1, 2])
      mock_learner.get_variables.assert_called_once_with(["a", "b"])
  
file_path: acme/acme/utils/frozen_learner_test.py
imports: from unittest import mock
  import acme
  from acme.utils import frozen_learner
  from absl.testing import absltest
label_desc: Use image node_id 4 for calling the FrozenLearnerTest obj's underlying member method code with example usage: obj.test_get_variables(mock_learner) without return types