Bowling Game: State Machine: Std::Variant: Step 31

Adding that missing code is easy:

        struct WaitingForFirstRollWith1Bonus : FirstRollUtils
        {
            State Update(int pins, int& score, int& frame) const
            {
                score += pins*2;
                if (IsStrike(pins)) {
                    ++frame;
                    return WaitingForFirstRollWith2Bonuses{};
                }
                return WaitingForSecondRollWith0Bonuses{pins};
            }
        };

Now, looking at all the first rolls states, something doesn’t look right to me:

        struct WaitingForFirstRollWith0Bonuses : FirstRollUtils
        {
            State Update(int pins, int& score, int& frame) const
            {
                score += pins;
                if (IsStrike(pins)) {
                    ++frame;
                    return WaitingForFirstRollWith2Bonuses{};
                }
                return WaitingForSecondRollWith0Bonuses{pins};
            }
        };
        struct WaitingForFirstRollWith1Bonus : FirstRollUtils
        {
            State Update(int pins, int& score, int& frame) const
            {
                score += pins*2;
                if (IsStrike(pins)) {
                    ++frame;
                    return WaitingForFirstRollWith2Bonuses{};
                }
                return WaitingForSecondRollWith0Bonuses{pins};
            }
        };
        struct WaitingForFirstRollWith2Bonuses : FirstRollUtils
        {
            State Update(int pins, int& score, int& frame) const
            {
                score += pins*2;
                if (IsStrike(pins)) {
                    ++frame;
                    return WaitingForFirstRollWith3Bonuses{};
                }
                return WaitingForSecondRollWith1Bonus{pins};
            }
        };
        struct WaitingForFirstRollWith3Bonuses : FirstRollUtils
        {
            State Update(int pins, int& score, int& frame) const
            {
                score += pins*3;
                if (IsStrike(pins)) {
                    ++frame;
                    if (frame == 10)
                        return LastFrameWith2Bonuses{};
                    return WaitingForFirstRollWith3Bonuses{};
                }
                return WaitingForSecondRollWith1Bonus{pins};
            }
        };

Only the last one is checking to see if we’re in the last frame, which needs to be handled specially. And that means that we’re missing (at least) 3 tests.

Let’s add a test for a strike in the last frame and then for the two bonus rolls, a strike and a 1:

	{"18 gutterballs, then two strikes and a bonus roll of 1 means score is 21", []() {
		Game game;
		RollMany(game, 18, 0);
		game.Roll(10); // strike
		game.Roll(10); // strike
		game.Roll(1);
		Assert::AreEqual(21, game.Score()); // game is over here
		Assert::ExpectingException<std::invalid_argument>([&game]() { game.Roll(0); });
	}},

Get all the tests to pass and then click next.