def test_add_defense_play_should_be_able_to_add(self):
        # Arrange
        play = Mock(spec=DefensePlay)

        # Act
        playbook = FootballPlaybook() \
                    .add_defense_play(play)

        # Assert
        self.assertTrue(play in playbook.get_defense_plays())
    def test_remove_defense_play_be_able_to_remove(self):
        # Arrange
        play = Mock(spec=DefensePlay)

        # Act
        playbook = FootballPlaybook() \
                    .add_defense_play(play) \
                    .remove_defense_play(play)

        # Assert
        self.assertFalse(play in playbook.get_defense_plays())