Raymond Yang

Intoduction:

Mockito is very useful for Junit test. This post will discuss how to use mockito to write a Junit. Here I will discuss the difference between Stub, Mock and Spy. And use mockito to give three example.

Stub, Mock and Spy

These three concept shares some points, and also has their own difference.

Stub is like you making the return value, everything is mocked.

/**
 * Stub
 */

@Mock
MockService mockService

@Test
public void test() {
    when(mockService...).thenReturn(...)
    Assert...
}

Mock means your call is mocked, but system respond is real, which means you don’t make the return value.

/**
 * Mock
 */

@Mock (answer = Answer.CALLS_REAL_METHODS)
MockService mockService

@Test
public void test() {
    mockService.API()
    Assert...
}

Spy is way beyond mock, both the call and system respond are real.

/**
 * Spy
 */

@Mock
MockService mockService

@Before
public void setup() {
    mockService = new MockService();
}

@Test
public void test() {
    mockService.API()
    assert...
}