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@ntk1000

TDD入門自分用メモ-20141121

Last updated at Posted at 2014-11-21

Part 1-8

  • 構造が似ているメソッドの...
Dollar.java

    Dollar times(int multiplier){
        return new Dollar(amount * multiplier);
    }
Franc.java

    Franc times(int multiplier){
        return new Franc(amount * multiplier);
    }
  • シグニチャを一致させる
Dollar.java

    Money times(int multiplier){
        return new Dollar(amount * multiplier);
    }
Franc.java

    Money times(int multiplier){
        return new Franc(amount * multiplier);
    }
  • サブクラスへの直接参照を減らしたい
DollarFrancTest.java

    @Test
    public void testMultiplication(){
        Money five = Money.dollar(5);
        assertEquals(new Dollar(10),five.times(2));
        assertEquals(new Dollar(15),five.times(3));
    }
  • Moneyにファクトリメソッドを導入し...
Money.java

    static Dollar dollar(int amount){
        return new Dollar(amount);
    }
  • Moneyを抽象クラスにしてtimesメソッドを定義する
Money.java

abstract class Money {

    protected int amount;

    public boolean equals(Object object){
        Money money = (Money)object;
        return amount == money.amount && getClass().equals(money.getClass());
    }

    static Money dollar(int amount){
        return new Dollar(amount);
    }

    abstract  Money times(int multiplier);
}
  • テストを修正する
DollarTest.java

    @Test
    public void testMultiplication(){
        Money five = Money.dollar(5);
        assertEquals(Money.dollar(10),five.times(2));
        assertEquals(Money.dollar(15),five.times(3));
    }

    @Test
    public void testEquality(){
        assertTrue(Money.dollar(5).equals(Money.dollar(5)));
        assertFalse(Money.dollar(5).equals(Money.dollar(6)));
        assertTrue(new Franc(5).equals(new Franc(5)));
        assertFalse(new Franc(5).equals(new Franc(6)));
        assertFalse(new Franc(5).equals(Money.dollar(5)));
    }
  • Francへの対応
FrancTest.java

    @Test
    public void testFrancMultiplication(){
        Money five = Money.franc(5);
        assertEquals(Money.franc(10),five.times(2));
        assertEquals(Money.franc(15),five.times(3));
    }
DollarTest.java

    @Test
    public void testMultiplication(){
        Money five = Money.dollar(5);
        assertEquals(Money.dollar(10),five.times(2));
        assertEquals(Money.dollar(15),five.times(3));
    }

    @Test
    public void testEquality(){
        assertTrue(Money.dollar(5).equals(Money.dollar(5)));
        assertFalse(Money.dollar(5).equals(Money.dollar(6)));
        assertTrue(Money.franc(5).equals(Money.franc(5)));
        assertFalse(Money.franc(5).equals(Money.franc(6)));
        assertFalse(Money.franc(5).equals(Money.dollar(5)));
    }
Money.java

abstract class Money {

    protected int amount;

    public boolean equals(Object object){
        Money money = (Money)object;
        return amount == money.amount && getClass().equals(money.getClass());
    }

    static Money dollar(int amount){
        return new Dollar(amount);
    }

    static Money franc(int amount){
        return new Franc(amount);
    }

    abstract  Money times(int multiplier);
}

この章で行ったこと

  1. 徐々に重複を取り除いた

  2. ファクトリメソッドを導入し、サブクラスの存在をテストから分離した

Part 1-9

通貨概念の導入

DollarFrancTest.java

    @Test
    public void testCurrency(){
        assertEquals("USD", Money.dollar(1).currency());
        assertEquals("CHF", Money.franc(1).currency());
    }
  • currency()の実装
Money.java

    abstract String currency();
Dollar.java

class Dollar extends Money {

    private String currency;

    Dollar(int amount){
        this.amount = amount;
        currency = "USD";
    }

    String currency(){
        return currency;
    }

    Money times(int multiplier){
        return new Dollar(amount * multiplier);
    }
}
Franc.java

class Franc extends Money{

    private String currency;

    Franc(int amount){
        this.amount = amount;
        currency = "CHF";
    }

    String currency(){
        return currency;
    }

    Money times(int multiplier){
        return new Franc(amount * multiplier);
    }
}
  • サブクラス間の重複する実装をスーパークラスに移動
Money.java

    protected String currency;

    String currency(){
        return currency;
    }
Dollar.java

class Dollar extends Money {

    Dollar(int amount){
        this.amount = amount;
        currency = "USD";
    }

    Money times(int multiplier){
        return new Dollar(amount * multiplier);
    }
}
Franc.java

class Franc extends Money{

    Franc(int amount){
        this.amount = amount;
        currency = "CHF";
    }

    Money times(int multiplier){
        return new Franc(amount * multiplier);
    }
}

  • 通貨文字列をファクトリメソッドに移動し、コンストラクタを共通化したいが...

  • コンストラクタに引数を追加すると

Franc.java

    Franc(int amount, String currency){
        this.amount = amount;
        this.currency = "CHF";
    }
  • Francをnewしているところの修正が必要
Money.java

    static Money franc(int amount){
        return new Franc(amount,null);
    }
  • ここはファクトリメソッド使うべきでは？
Franc.java

    Money times(int multiplier){
        return new Franc(amount * multiplier,null);
    }
  • timesがコンストラクタを使っていることに気づいたので、ファクトリメソッドを使うよう変更する
Franc.java

    Money times(int multiplier){
        return Money.franc(amount * multiplier);
    }
  • ファクトリメソッドが文字列を渡せるようになる
Money.java

    static Money franc(int amount){
        return new Franc(amount,"CHF");
    }
Franc.java

    Franc(int amount, String currency){
        this.amount = amount;
        this.currency = currency;
    }
  • 大きな変更を細かな変更に分割し、ミスを減らす
  • Dollarに同じ変更を適用し、問題ないことを確認する
Money.java

    static Money dollar(int amount){
        return new Dollar(amount,"USD");
    }
Dollar.java

class Dollar extends Money {

    Dollar(int amount, String currency){
        this.amount = amount;
        this.currency = currency;
    }

    Money times(int multiplier){
        return Money.dollar(amount * multiplier);
    }
}

  • これでコンストラクタの実装が共通かできた
    ``` Money.java

    Money(int amount, String currency){
    this.amount = amount;
    this.currency = currency;
    }


``` Franc.java

    Franc(int amount, String currency){
        super(amount,currency);
    }
Dollar.java

    Dollar(int amount, String currency){
        super(amount,currency);
    }

この章で行ったこと

  1. コンストラクタの共通化

  2. 小さなステップでリファクタリングした

DollarTest.java

public class DollarTest {

    @Test
    public void testMultiplication(){
        Money five = Money.dollar(5);
        assertEquals(Money.dollar(10),five.times(2));
        assertEquals(Money.dollar(15),five.times(3));
    }

    @Test
    public void testEquality(){
        assertTrue(Money.dollar(5).equals(Money.dollar(5)));
        assertFalse(Money.dollar(5).equals(Money.dollar(6)));
        assertTrue(Money.franc(5).equals(Money.franc(5)));
        assertFalse(Money.franc(5).equals(Money.franc(6)));
        assertFalse(Money.franc(5).equals(Money.dollar(5)));
    }

    @Test
    public void testCurrency(){
        assertEquals("USD", Money.dollar(1).currency());
        assertEquals("CHF", Money.franc(1).currency());
    }
}
FrancTest.java

public class FrancTest {

    @Test
    public void testFrancMultiplication(){
        Money five = Money.franc(5);
        assertEquals(Money.franc(10),five.times(2));
        assertEquals(Money.franc(15),five.times(3));
    }
}
Money.java

abstract class Money {

    protected int amount;

    public boolean equals(Object object){
        Money money = (Money)object;
        return amount == money.amount && getClass().equals(money.getClass());
    }

    static Money dollar(int amount){
        return new Dollar(amount,"USD");
    }

    static Money franc(int amount){
        return new Franc(amount,"CHF");
    }

    abstract  Money times(int multiplier);

    protected String currency;

    String currency(){
        return currency;
    }

    Money(int amount, String currency){
        this.amount = amount;
        this.currency = currency;
    }
}
Dollar.java

class Dollar extends Money {

    Dollar(int amount, String currency){
        super(amount,currency);
    }

    Money times(int multiplier){
        return Money.dollar(amount * multiplier);
    }
}
Franc.java

pclass Franc extends Money{

    Franc(int amount, String currency){
        super(amount,currency);
    }

    Money times(int multiplier){
        return Money.franc(amount * multiplier);
    }
}
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