Exception : mockito wanted but not invoked, Actually there were zero interactions with this mock

Question

I have interface

Interface MyInterface {
  myMethodToBeVerified (String, String);
}

And implementation of interface is

class MyClassToBeTested implements MyInterface {
   myMethodToBeVerified(String, String) {
    …….
   }
}

I have another class

class MyClass {
    MyInterface myObj = new MyClassToBeTested();
    public void abc(){
         myObj.myMethodToBeVerified (new String(“a”), new String(“b”));
    }
}

I am trying to write JUnit for MyClass. I have done

class MyClassTest {
    MyClass myClass = new MyClass();
  
    @Mock
    MyInterface myInterface;

    testAbc(){
         myClass.abc();
         verify(myInterface).myMethodToBeVerified(new String(“a”), new String(“b”));
    }
}

But I am getting mockito wanted but not invoked, Actually there were zero interactions with this mock at verify call.

can anyone suggest some solutions.

Answer 1

You need to inject mock inside the class you're testing. At the moment you're interacting with the real object, not with the mock one. You can fix the code in a following way:

void testAbc(){
     myClass.myObj = myInteface;
     myClass.abc();
     verify(myInterface).myMethodToBeVerified(new String("a"), new String("b"));
}

although it would be a wiser choice to extract all initialization code into @Before

@Before
void setUp(){
     myClass = new myClass();
     myClass.myObj = myInteface;
}

@Test
void testAbc(){
     myClass.abc();
     verify(myInterface).myMethodToBeVerified(new String("a"), new String("b"));
}

Answer 2

Your class MyClass creates a new MyClassToBeTested, instead of using your mock. My article on the Mockito wiki describes two ways of dealing with this.

Answer 3

@Jk1's answer is fine, but Mockito also allows for more succinct injection using annotations:

@InjectMocks MyClass myClass; //@InjectMocks automatically instantiates too
@Mock MyInterface myInterface

But regardless of which method you use, the annotations are not being processed (not even your @Mock) unless you somehow call the static MockitoAnnotation.initMocks() or annotate the class with @RunWith(MockitoJUnitRunner.class).

Answer 4

@jk1 answer is perfect, since @igor Ganapolsky asked, why can't we use Mockito.mock here? i post this answer.

For that we have provide one setter method for myobj and set the myobj value with mocked object.

class MyClass {
    MyInterface myObj;

    public void abc() {
        myObj.myMethodToBeVerified (new String("a"), new String("b"));
    }

    public void setMyObj(MyInterface obj)
    {
        this.myObj=obj;
    }
}

In our Test class, we have to write below code

class MyClassTest {

MyClass myClass = new MyClass();

    @Mock
    MyInterface myInterface;

    @test
    testAbc() {
        myclass.setMyObj(myInterface); //it is good to have in @before method
        myClass.abc();
        verify(myInterface).myMethodToBeVerified(new String("a"), new String("b"));
     }
}