敏捷开发第6章 一次编程实践

Bob Koss 与 Bob Martin展示结对编程。用TDD的开发模式做一个计算保龄球比赛得分程序。

首先，他们创建了一个测试验收用例。画了一个简单的UML图，便从写测试用例开始编程。

一开始的设计是这样的：

分为三个类：

1. Game类
2. Game类包含Frame类，1:10
3. Frame类包含Throw类，1..3

然后，他们发现不需要Throw类，甚至也不需要Frame类。接着，不断的按功能增加单元测试，单元测试不通过则编写业务代码，通过后再重构，直到代码看上去没有坏味道为止。比如补中与全中的计分功能。整个开发过程是互相提出想法，用代码实践想法，提出修改意见，用代码实践修改意见。

最后代码：

Game：

 public class Game
    {
        int currentFrame = 0;
        bool isFirstThrow = true;
        Scorer scorer = new Scorer();

        public int Score { get { return ScoreForFrame(currentFrame); } }

        public void Add(int pins)
        {
            scorer.AddThrow(pins);
            AdjustCurrentFrame(pins);
        }

        void AdjustCurrentFrame(int pins)
        {
            if (LastBallInFrame(pins)) AdvanceFrame();
            else isFirstThrow = false;
        }

        bool LastBallInFrame(int pins)
        {
            return Strike(pins) || !isFirstThrow;
        }

        bool Strike(int pins)
        {
            return isFirstThrow && pins == 10;
        }

        void AdvanceFrame()
        {
            currentFrame++;
            if (currentFrame > 10) currentFrame = 10;
        }

        public int ScoreForFrame(int theFrame)
        {
            return scorer.ScoreForFrame(theFrame);
        }
    }

Scorer：

 class Scorer
    {
        int ball;
        int[] throws = new int[21];
        int currentThrow;

        int NextBallForSpare { get { return throws[ball + 2]; } }
        int NextTwoBallsForStrike { get { return throws[ball + 1] + throws[ball + 2]; } }
        int TwoBallsInFrame { get { return throws[ball] + throws[ball + 1]; } }

        bool Strike()
        {
            return throws[ball] == 10;
        }

        bool Spare()
        {
            return throws[ball] + throws[ball + 1] == 10;
        }

        public void AddThrow(int pins)
        {
            throws[currentThrow++] = pins;
        }

        public int ScoreForFrame(int theFrame)
        {
            ball = 0;
            int score = 0;
            for (int currentFrame = 0; currentFrame < theFrame; currentFrame++)
            {
                if (Strike())
                {
                    score += 10 + NextTwoBallsForStrike;
                    ball++;
                }
                else if (Spare())
                {
                    score += 10 + NextBallForSpare;
                    ball += 2;
                }
                else
                {
                    score += TwoBallsInFrame;
                    ball += 2;
                }
            }
            return score;
        }
    }

GameTest：

public class GameTest
{
    Game game;

    [SetUp]
    public void SetUp()
    {
        game = new Game();
    }

    [Test]
    public void TestTwoThrowNoMark()
    {
        game.Add(5);
        game.Add(4);
        Assert.AreEqual(9, game.Score);
    }

    [Test]
    public void TestFourThrowNoMark()
    {
        game.Add(5);
        game.Add(4);
        game.Add(7);
        game.Add(2);
        Assert.AreEqual(18, game.Score);
        Assert.AreEqual(9, game.ScoreForFrame(1));
        Assert.AreEqual(18, game.ScoreForFrame(2));
    }

    [Test]
    public void TestSimpleSpare()
    {
        game.Add(3);
        game.Add(7);
        game.Add(3);
        Assert.AreEqual(13, game.ScoreForFrame(1));
    }

    [Test]
    public void TestSimpleFrameAfterSpare()
    {
        game.Add(3);
        game.Add(7);
        game.Add(3);
        game.Add(2);
        Assert.AreEqual(13, game.ScoreForFrame(1));
        Assert.AreEqual(18, game.ScoreForFrame(2));
        Assert.AreEqual(18, game.Score);
    }

    [Test]
    public void TestSimpleStrike()
    {
        game.Add(10);
        game.Add(3);
        game.Add(6);
        Assert.AreEqual(19, game.ScoreForFrame(1));
        Assert.AreEqual(28, game.Score);
    }

    [Test]
    public void TestPerfectGame()
    {
        for (int i = 0; i < 12; i++) game.Add(10);
        Assert.AreEqual(300, game.Score);
    }

    [Test]
    public void TestEndOfArray()
    {
        for (int i = 0; i < 9; i++)
        {
            game.Add(0);
            game.Add(0);
        }
        game.Add(2);
        game.Add(8);
        game.Add(10);
        Assert.AreEqual(20, game.Score);
    }

    [Test]
    public void TestSampleGame()
    {
        game.Add(1);
        game.Add(4);
        game.Add(4);
        game.Add(5);
        game.Add(6);
        game.Add(4);
        game.Add(5);
        game.Add(5);
        game.Add(10);
        game.Add(0);
        game.Add(1);
        game.Add(7);
        game.Add(3);
        game.Add(6);
        game.Add(4);
        game.Add(10);
        game.Add(2);
        game.Add(8);
        game.Add(6);
        Assert.AreEqual(133, game.Score);
    }

    [Test]
    public void TestHeartBreak()
    {
        for (int i = 0; i < 11; i++) game.Add(10);
        game.Add(9);
        Assert.AreEqual(299, game.Score);
    }

    [Test]
    public void TestTenthFrameSpare()
    {
        for (int i = 0; i < 9; i++) game.Add(10);
        game.Add(9);
        game.Add(1);
        game.Add(1);
        Assert.AreEqual(270, game.Score);
    }