Mockito

1. Add the ‘mockito-all’ dependency to your build.gradle file

dependencies {
    
    ...

    testCompile group: 'org.mockito', name: 'mockito-all', version: '1.9.5'
    
    ...

}

Please add the above dependency in your build.gradle code.

2. Make the sample VO Object.

We need a sample VO Object for knowing how does the Mockito Test is configured. so We will make the PersonVO like the below code.

@Data
public class PersonVO {
    String name;
    int age;
    String major;
}

3. @Mock

You can create the new object using this annotation. It’s really similar with the ‘autowired’ annotation in Spring but Mock annotation is only able to use in Test case.

import org.mockito.Mock;

public class PersonVOTest {

    @Mock
    PersonVO;

}

at the above code, You can see the code creating the PersonVO object using @Mock annotation. Actually You need a one more code for creating the object using @Mock. It’s like the below

import org.mockito.Mock;

public class PersonVOTest {

    @Mock
    PersonVO;

    @Before
    public void setUp() {
        MockitoAnnotations.initMocks(this);
    }

}

When you use the @Mock annotation, you should add ‘MockitoAnnotations.initMock(this)’ code in your test case. It’s like the constructor in Java.

4. @InjectMocks

For understanding the @InjectMocks Let’s define new class named ‘PersonService’ like the below.

public class PersonService {

    @Autowired
    PersonVO personVO;

}

If you type the code like the below then you will face a problem what you can’t control the PersonVO object in the PersonService.

import org.mockito.Mock;

public class PersonVOTest {

    @Mock
    PersonService personService;

}

in this case, if you use the @InjectMocks annotation, then you are able to solve this problem.

import org.mockito.Mock;

public class PersonVOTest() {
    
    @Mock
    PersonVO personVO;

    @InjectMocks
    PersonService personService;

    @Before
    public void setUp() {
        MockitoAnnotations.initMocks(this);
    }

}

5. when().thenReturn()

import org.mockito.Mock;

public class PersonVOTest() {
    
    @Mock
    PersonVO personVO;

    @InjectMocks
    PersonService personService;

    @Before
    public void setUp() {
        MockitoAnnotations.initMocks(this);
    }

    @Test
    public void example() {
        when(personVO.getName()).thenReturn("Mark");
        // when you call the 'personVO.getName()' function then please return the 'Mark' String.

        when(personVO.getAge()).thenReturn(20);
        // when you call the 'personVO.getAge()' function then return '20'.

        when(personVO.getMajor()).thenReturn("Computer Engineering");
        // when you call the 'personVO.getMajor()' then return 'Computer Engineering'.

        assertTrue(personVO.getName().equals("Mark"))                           // True
        assertTrue(personVO.getAge() == 20)                                     // True
        assertTrue(personVO.getMajor().equals("Computer Engineering"))          // True

        assertTrue(personVO.getName().equals("Chris"))                          // False
        assertTrue(personVO.getAge() == 30)                                     // False
        assertTrue(personVO.getMajor().equals("Electric Engineering"))          // False
    }
}

6. doThrow()

import org.mockito.Mock;

public class PersonVOTest() {
    
    @Mock
    PersonVO personVO;

    @InjectMocks
    PersonService personService;

    @Before
    public void setUp() {
        MockitoAnnotations.initMocks(this);
    }

    @Test(expected = IllegalArgumentException.class)
    public void example() {
        doThrow(new IllegalArgumentException()).when(p).setName(eq("JDM"));
        // eq...
        personVO.setName("JDM");
    }
}

7. doNothing()

import org.mockito.Mock;

public class PersonVOTest() {
    
    @Mock
    PersonVO personVO;

    @InjectMocks
    PersonService personService;

    @Before
    public void setUp() {
        MockitoAnnotations.initMocks(this);
    }

    @Test
    public void example(){
        doNothing().when(personVO).setAge(anyInt());
        verify(personVO).setAge(anyInt());
    }
}