Bowling Game: State Machine: Unique_Ptr: Step 28

Here are the refactored AddStrike and AddRoll methods (refactoring to tabular switch statement):

        void AddStrike()
        {
            switch (bonusRolls)
            {
            case Bonus::NoBonusRolls        : score += 10; bonusRolls = Bonus::TwoBonusRolls;        ++frame; break;
            case Bonus::OneBonusRoll        : score += 20; bonusRolls = Bonus::TwoBonusRolls;        ++frame; break;
            case Bonus::TwoBonusRolls       : score += 20; bonusRolls = Bonus::TwoStrikesBonusRolls; ++frame; break;
            case Bonus::TwoStrikesBonusRolls: score += 30; bonusRolls = Bonus::TwoStrikesBonusRolls; ++frame; break;
            }
        }
        void AddRoll(int pins)
        {
            if ((frame > 10) || ((frame == 10) && (bonusRolls == Bonus::NoBonusRolls)))
                throw std::out_of_range("can't roll after game has ended");

            if (frame < 10)
                score += pins;

            switch (bonusRolls)
            {
            case Bonus::NoBonusRolls        :                                                     break;
            case Bonus::OneBonusRoll        : score += pins;   bonusRolls = Bonus::NoBonusRolls;  break;
            case Bonus::TwoBonusRolls       : score += pins;   bonusRolls = Bonus::OneBonusRoll;  break;
            case Bonus::TwoStrikesBonusRolls: score += pins*2; bonusRolls = Bonus::TwoBonusRolls; break;
            }
        }

The tests all still pass. But this code now makes clear two things: I’m missing a ton of tests/cases in the AddSpare method, and we’re not checking for being in the last frame in the AddSpare and AndStrike method.

Looking very carefully at the AddRoll method, I see we can extract the switch case into its own method and call it from AddStrike (and in the near future, AddSpare).

What to do first? One thing I often do when TDDing is keep a yellow pad next to my computer. When I think of tests I still need to write, I write a note to myself on the yellow pad so that I don’t forget.

Since the switch statements in the AddRoll and AddStrike methods don’t look identical yet, maybe we should concentrate on the AddSpare method, to help clear up what the commonality is. To do that, let’s write the next test: if we’ve rolled a strike, followed by a spare, we need to handle the bonus rolls properly for the second roll of the spare. So, a strike, a spare (say, two 5s) and one more roll, say a 1: that adds up to 32.

Let’s write that test, and then click next.