自動販売機をTDDで実装する

例題
＞ TDDBC大阪

購入できるかどうかを調べるために、isPurchacable() メソッドを追加する。

	@Test
	public void testIsPurchacable() {
		VendingMachine vm = new VendingMachine();
		boolean b = vm.isPurchacable();
		assertThat(b, is(false));
	}

Eclipseでメソッドを生成するとテストをパスするようになる。

	public boolean isPurchacable() {
		return false;
	}

500円を投入すると購入可能になるテストを追加する。

	@Test
	public void testIsPurchacable() {
		VendingMachine vm = new VendingMachine();
		boolean b = vm.isPurchacable();
		assertThat(b, is(false));
		vm.throwInto(500);
		b = vm.isPurchacable();
		assertThat(b, is(true));
	}

自動販売機の購入の動作を実装する

お金を入れてボタンを押すとジュースとおつりが出てくる。

それっぽいテストを書いてみる。
出てくるもの（ジュースとおつり）をまとめて Output クラスとしておく。
VendingMachineTest.java

	@Test
	public void testPurchace() {
		VendingMachine vm = new VendingMachine();
		vm.throwInto(100);
		vm.throwInto(10);
		vm.throwInto(10);
		Output o = vm.purchace();
		assertThat(j, is(1));
		assertThat(change, is(0));
	}

Output.java

public class Output {
	private int juiceCount;
	private int change;

	public Output(int juiceCount, int change) {
		this.juiceCount = juiceCount;
		this.change = change;
	}

	public int getJuiceCount() {
		return juiceCount;
	}

	public int getChange() {
		return change;
	}
}

ここまでのコードは以下のとおり。
VendingMachineTest.java

import static org.hamcrest.CoreMatchers.*;
import static org.junit.Assert.*;

import org.junit.Test;


public class VendingMachineTest {

	@Test
	public void testThrowInto() {
		VendingMachine vm = new VendingMachine();
		int change = vm.throwInto(10);
		assertThat(change, is(0));
		int total = vm.getTotal();
		assertThat(total, is(10));
		change = vm.throwInto(50);
		assertThat(change, is(0));
		total = vm.getTotal();
		assertThat(total, is(60));
	}

	@Test
	public void testThrowIntoNotAccept() {
		VendingMachine vm = new VendingMachine();
		int change = vm.throwInto(1);
		assertThat(change, is(1));
		int total = vm.getTotal();
		assertThat(total, is(0));
		change = vm.throwInto(5);
		assertThat(change, is(5));
		change = vm.throwInto(2000);
		assertThat(change, is(2000));
		change = vm.throwInto(5000);
		assertThat(change, is(5000));
		change = vm.throwInto(10000);
		assertThat(change, is(10000));
	}

	@Test
	public void testThrowIntoRefund() {
		VendingMachine vm = new VendingMachine();
		int change = vm.throwInto(10);
		assertThat(change, is(0));
		int total = vm.getTotal();
		assertThat(total, is(10));
		int refund = vm.refund();
		assertThat(refund, is(10));
		total = vm.getTotal();
		assertThat(total, is(0));
		change = vm.throwInto(100);
		assertThat(change, is(0));
		total = vm.getTotal();
		assertThat(total, is(100));
		change = vm.throwInto(500);
		assertThat(change, is(0));
		total = vm.getTotal();
		assertThat(total, is(600));
		refund = vm.refund();
		assertThat(refund, is(600));
	}

	@Test
	public void testGetJuice() {
		VendingMachine vm = new VendingMachine();
		String name = vm.getJuiceName();
		assertThat(name, is("コーラ"));
		int price = vm.getJuicePrice();
		assertThat(price, is(120));
		int stock = vm.getJuiceStock();
		assertThat(stock, is(5));
	}

	@Test
	public void testIsPurchacable() {
		VendingMachine vm = new VendingMachine();
		boolean b = vm.isPurchacable();
		assertThat(b, is(false));
		vm.throwInto(500);
		b = vm.isPurchacable();
		assertThat(b, is(true));
	}

	@Test
	public void testPurchace() {
		VendingMachine vm = new VendingMachine();
		vm.throwInto(100);
		vm.throwInto(10);
		vm.throwInto(10);
		Output o = vm.purchace();
		assertThat(o.getJuiceCount(), is(1));
		assertThat(o.getChange(), is(0));
		int total = vm.getTotal();
		assertThat(total, is(0));
	}
}

VendingMachine.java

public class VendingMachine {
	private int total;

	public int throwInto(int yen) {
		if (yen == 1) return 1;
		if (yen == 5) return 5;
		if (yen == 2000) return 2000;
		if (yen == 5000) return 5000;
		if (yen == 10000) return 10000;
		total += yen;
		return 0;
	}

	public int getTotal() {
		return total;
	}

	public int refund() {
		int refund = total;
		total = 0;
		return refund;
	}

	public String getJuiceName() {
		return "コーラ";
	}

	public int getJuicePrice() {
		return 120;
	}

	public int getJuiceStock() {
		return 5;
	}

	public boolean isPurchacable() {
		if (getJuiceStock() == 0) return false;
		return total >= getJuicePrice();
	}

	public Output purchace() {
		return new Output(1, 0);
	}
}

Juice.java

public class Juice {
	private String name;
	private int price;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getPrice() {
		return price;
	}
	public void setPrice(int price) {
		this.price = price;
	}
}

500円を投入して購入する。

VendingMachineTest.java

	@Test
	public void testPurchace500() {
		VendingMachine vm = new VendingMachine();
		vm.throwInto(500);
		Output o = vm.purchace();
		assertThat(o.getJuiceCount(), is(1));
		assertThat(o.getChange(), is(380));
		int total = vm.getTotal();
		assertThat(total, is(0));
	}

1000円を投入して購入する。

VendingMachineTest.java

	@Test
	public void testPurchace1000() {
		VendingMachine vm = new VendingMachine();
		vm.throwInto(1000);
		Output o = vm.purchace();
		assertThat(o.getJuiceCount(), is(1));
		assertThat(o.getChange(), is(880));
		int total = vm.getTotal();
		assertThat(total, is(0));
	}

在庫切れを実装する。
500円を投入して購入する。

VendingMachineTest.java

	@Test
	public void testPurchace500() {
		VendingMachine vm = new VendingMachine();
		vm.throwInto(1000);
		Output o = vm.purchace();
		assertThat(o.getJuiceCount(), is(1));
		assertThat(o.getChange(), is(880));
		int stock = vm.getJuiceStock();
		assertThat(stock, is(4));
		for (int i = 0; i < 4; i++) {
			vm.throwInto(500);
			o = vm.purchace();
		}
		stock = vm.getJuiceStock();
		assertThat(stock, is(0));
		vm.throwInto(500);
		o = vm.purchace();
		assertThat(o.getJuiceCount(), is(0));
		assertThat(o.getChange(), is(0));
		int total = vm.getTotal();
		assertThat(total, is(500));
	}

売上高を確認できるようにする。

VendingMachineTest.java

	@Test
	public void testSale() {
		VendingMachine vm = new VendingMachine();
		int sale = vm.getSale();
		assertThat(sale, is(0));
		vm.throwInto(500);
		vm.purchace();
		sale = vm.getSale();
		assertThat(sale, is(120));
	}