如何模拟从 Junit 调用内部方法

问题描述

我有 MyClass，我正在为每个方法做一个测试类 (Method1Test)

I have MyClass and I am doing a test-class for every method (Method1Test)

public class MyClass {
    public int method1(){
        int a = method2();
        return a;
    }
    public int method2(){
        return 0;
    }
}

@RunWith(MockitoJUnitRunner.class)
public class Method1Test {
    @InjectMocks
    private MyClass myClass = new MyClass();
    @Before
    public void setup(){}
    @Test
    public void test01(){
        Mockito.when(myClass.method2()).thenReturn(25);
        int a = myClass.method1();
        assertTrue("We did it!!!",a==25);
    }
}

问题是我无法模拟对 method2 的调用以使其返回不同的值.Mockito 语句不起作用.

The problem is that I am not able to mock the call to method2 to make it return a diferent value. The Mockito sentence don't do the work.

非常感谢^_^

推荐答案

你必须在被测类上创建一个 spy 并通过重新定义 method2() 的行为来部分模拟它间谍

You have to create a spy on the class-under-test and partially mock it by redefining the behavior for the method2() of the spy

import static org.junit.Assert.assertEquals;
import static org.mockito.Mockito.spy;
import static org.mockito.Mockito.when;


public class Method1Test {

  private MyClass myClass = new MyClass();

  @Test
  public void test01(){
    //given
    MyClass spy = spy(myClass); //create a spy for class-under-test
    when(spy.method2()).thenReturn(25); //partially override behavior of the spy
    //when
    int a = spy.method1(); //make the call to method1 of the _spy_!
    //then
    assertEquals(25, a);
  }
}

除此之外，您既不需要 Mockito Runner 也不需要 @InjectMocks 进行测试，因为您没有将 @Mock 带注释的模拟注入到被测类.

Apart from this, you don't require neither the Mockito Runner nor the @InjectMocks for your test as you're doing no injection of @Mock annotated mocks into the class-under-test.

此外，assertTrue 语句中的消息仅在断言的条件 NOT 满足时才会显示.所以应该是至少我们失败了！！！";)

Further, the message in the assertTrue statement is only displayed, when the condition of the assertion is NOT fulfilled. So it should be at least "We failed!!!" ;)

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