java - 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"));
}