java - Junit 测试 - 没有我能看到的错误？

Question

我试图对一种方法使用 Junit 测试，但测试失败了，尽管“预期”与“是……”相同。我想知道是什么问题？lowerRate 方法只是一种将“HotelRoom”作为输入并以 10% 折扣输出价格的方法。谢谢这是我的测试代码:

@Test
public void testLowerRate() {
    System.out.println("lowerRate");
    HotelRoom room = new HotelRoom(4, 300, "N");
    HotelRoom instance = new HotelRoom(0, 0, "N");
    HotelRoom expResult = new HotelRoom(4, 270, "N");
    HotelRoom result = instance.lowerRate(room);
    assertEquals(expResult, result);

}
@Test
@SuppressWarnings("empty-statement")
public void testLowerRate2() {
    System.out.println("lowerRate");
    HotelRoom room = new HotelRoom(4, 100, "N");
    HotelRoom instance = new HotelRoom(0, 0, "N");
    HotelRoom expResult = new HotelRoom(4, 90, "N");
    HotelRoom result = instance.lowerRate(room);
    assertEquals(expResult, result);

}
@Test
public void testLowerRate3() {
    System.out.println("lowerRate");
    HotelRoom room = new HotelRoom(4, 1000, "N");
    HotelRoom instance = new HotelRoom(0, 0, "N");
    HotelRoom expResult = new HotelRoom(4, 900, "N");
    HotelRoom result = instance.lowerRate(room);
    assertEquals(expResult, result);

}
}

编辑 ------

程序代码如下:

class HotelRoom {

private int numofBeds;
private double rateperNight;
private String YorNoceanView;

HotelRoom(int input1, double input2, String input3) {
    numofBeds = input1;
    rateperNight = input2;
    YorNoceanView = input3;

}

public int getnumofBeds() {
    return numofBeds;
}

public void setnumofBeds(int numofBeds) {
    this.numofBeds = numofBeds;
}

public double getrateperNight() {
    return rateperNight;
}

public void setrateperNight(double rate) {
    this.rateperNight = rateperNight;
}

public String getYorNoceanView() {
    return YorNoceanView;
}

public void setYorNoceanView(String YorNoceanView) {
    this.YorNoceanView = YorNoceanView;
}

@Override
public String toString() {
    return "Hotel Room{" + "Title= " + numofBeds + ", Rate per night= $" + rateperNight + ", Ocean View (Y or N)=" + YorNoceanView + "}";

}

String roomUnder(HotelRoom room, double price) {
    if (room.getrateperNight() > price) {
        return "The room costs more than the given price";
    }
    if (room.getrateperNight() < price) {
        return "The room costs less than the given price";
    }
    else 
        return "The room costs as much as the given price.";
}
HotelRoom lowerRate(HotelRoom room) {
    room.rateperNight = 0.9 * room.rateperNight;
    return room;
}
}

public class Chpt2930HotelRoom {

/**
 * @param args the command line arguments
 */
public static void main(String[] args) {

    int num1 = 1;
    int num2 = 2;
    String input = "input";

    Scanner scan = new Scanner(System.in);
    Scanner user = new Scanner(System.in);
    System.out.print("Enter number of Beds: ");
    int nextLineBeds = scan.nextInt();
    HotelRoom HotelR = new HotelRoom(num1, num2, input);
    HotelR.setnumofBeds(nextLineBeds);
    System.out.println();


    System.out.print("Enter rate per night in Dollars: $");
    double nextLineRate = scan.nextDouble();
    HotelR.setrateperNight(nextLineRate);
    System.out.println();


    System.out.print("Enter whether the room has an ocean view (Y or N): ");
    String nextLineOcean = user.nextLine();
    HotelR.setYorNoceanView(nextLineOcean);
    System.out.println();

    System.out.println(HotelR.toString());
}
}

Answer 1

您缺少一些非常基本的东西。您的 lowerRate 方法返回一个 HotelRoom 类的对象，您正在使用 assertEquals 方法将该对象等同于一个完全不同的对象实例。这必然使对象引用相等(因为您没有覆盖 equals() 方法)。由于是两个不同的对象，它们的引用也不同，因此您的断言失败。

因为你想根据你的 rate 属性来均衡对象，那么你需要像这样重写 HotelRoom 类的 equals 方法:

@Override
public boolean equals(Object obj){

    if(obj instanceof HotelRoom) {
       if( Math.abs(this.rateperNight - ((HotelRoom) obj).rateperNight) < .000001) {
            return true;
       }
    }
    return false;
}

只有这样，您的酒店房间才会与您的期望进行比较。

参见:

• Object.equals()

• Object.hashCode()