Question

我有一个非常小的类 BuildThreeObjects ，它使用私有int变量 numObjects 创建最多3个对象来存储计数。如果计数是＆lt; 3，返回一个新的Object，否则返回null。

有人可以指导我如何使用JUnit创建最多3个对象。查看API并没有多大帮助。我假设会使用assertNotNull或assertNull，但我想不出怎么做。

// BuildThreeObjects类的代码

public class BuildThreeObjects {
    private int numObjects = 0;

    public Object buildObject() {
        if (numObjects<3) {
                numObjects++;
            return new Object();
        }
        else return null;
    }
}

// JUnit类中的代码;所有不必要的代码都省略了

private BuildThreeObjects bto;

@Before
public void setUp() throws Exception {
    bto = new BuildThreeObjects();
}

@Test
public void testBuild() {
    assertNotNull(bto.buildObject());
}

// assertNotNull passes and assertNull fails as it only checks the first object creation

Answer 1

你的意思是这样的吗？

class BuildThreeObjects{
    int count = 0;
    public Object buildObject(){
        if(count >= 3){
            return null;
        } else {
            count++;
            return new Object();
        }
    }
}

private BuildThreeObjects bto;

@Before
public void setUp() throws Exception {
    bto = new BuildThreeObjects();
}

@Test
public void testBuild() {
    assertNotNull(bto.buildObject());
    System.out.println(bto.count);
    assertNotNull(bto.buildObject());
    System.out.println(bto.count);
    assertNotNull(bto.buildObject());
    System.out.println(bto.count);
    assertNull(bto.buildObject());
    System.out.println(bto.count);
}

// with for loop

for(int i=0; i < 100; i++){
        if(i < 3){
            assertNotNull(bto.buildObject());
            System.out.println(bto.count);
        } else {
             assertNull(bto.buildObject());
               System.out.println(bto.count);
        }
    }

Answer 2

按字面意思做：

assertNotNull(createObject());

assertNotNull(createObject());

assertNotNull(createObject());

assertNull(createObject());

如果它更具表现力，你也可以使用for循环。

JUnit - 测试最大创建对象数

2 个答案: