def METHOD_NAME(self):
    nr_evaluations = 1
    metrics = self.learner.eval(self.env, nr_evaluations=nr_evaluations)
    self.assertTrue(len(metrics['episode_rewards']) == nr_evaluations, "Episode rewards have incorrect length.")
    self.assertTrue((np.array(metrics['episode_rewards']) <= 0.0).all(), "Test reward not below 0.")
    self.assertTrue((np.array(metrics['episode_lengths']) >= 0.0).all(), "Test episode lengths is negative")