test_scoreCounter.py

class ScoreCounter:

    def __init__(self):
        self.pins_down = None

    def roll(self, pins_down):
        self.pins_down = pins_down

    def score(self):
        return self.pins_down


def test_if_zero_pin_down_score_zero():
    score_counter = ScoreCounter()
    score_counter.roll(0)
    score = score_counter.score()
    assert (0 == score)


def test_single_shot_returns_number_pin_down():
    score_counter = ScoreCounter()
    score_counter.roll(4)
    score = score_counter.score()
    assert (4 == score)