盒装饮料 自动售货机的JAVA单元测试代码

盒装饮料自动售货机的Java单元测试通常会针对关键功能模块编写，例如货币识别、商品选择、付款处理等。下面是一个简化的例子，假设我们有一个`CoinDetector`类负责接收硬币并返回总金额，以及一个`DrinkMachine`类负责售出饮料：

// CoinDetector.java
public class CoinDetector {
    public int detectCoins(Coin[] coins) {
        // ...实际的硬币检测逻辑...
    }
}

// DrinkMachine.java
public class DrinkMachine {
    private final CoinDetector detector;
    
    public DrinkMachine(CoinDetector detector) {
        this.detector = detector;
    }

    public void purchase(Drink drink, Coin[] coins) {
        int amountDue = drink.getPrice();
        int totalCollected = detector.detectCoins(coins);
        if (totalCollected >= amountDue) {
            dispenseDrink(drink);
        } else {
            throw new InsufficientFundsException();
        }
    }
}

// Unit test for DrinkMachine
import org.junit.Test;
import static org.junit.Assert.*;

public class DrinkMachineTest {
    @Test
    public void testPurchaseSuccess() {
        // 测试有足够的硬币购买一瓶水
        CoinDetector mockDetector = mock(CoinDetector.class); // 创建模拟对象
        when(mockDetector.detectCoins(any())).thenReturn(50); // 模拟检测结果
        DrinkMachine machine = new DrinkMachine(mockDetector);
        
        Coin[] coins = {new Quarter(), new Nickel(), new Penny()};
        machine.purchase(new Water(), coins); // 饮料应该是成功购买

        verify(mockDetector).detectCoins(coins); // 确保检测方法被调用
    }

    @Test
    public void testPurchaseInsufficientFunds() {
        // 测试硬币不足的情况
        CoinDetector mockDetector = mock(CoinDetector.class);
        when(mockDetector.detectCoins(any())).thenReturn(10); // 模拟不足以支付的金额
        
        DrinkMachine machine = new DrinkMachine(mockDetector);
        try {
            machine.purchase(new Water(), coins); // 预期会抛出异常
            fail("Expected an InsufficientFundsException");
        } catch (InsufficientFundsException e) {
            // 正确的行为
        }
    }
}