Inject mock object without java interface for unit testing

Question

My java project has multiple layers such as Controller (depends on) Service (depends on) DAO. My goal is to unit test Controller.

I created Mock service object to inject it in to Controller class.

After googling , Ive learnt that I could use java interface to do so.

Ideally, service layer does not need an interface.

I wonder if there is a different approach to inject mock object without a java interface.

Stefan Birkner · Accepted Answer · 2013-11-21 07:40:43Z

6

There are mocking libraries like Mockito, which could create mocks for classes without the need of interfaces.

MyService serviceMock = org.Mockito.mock(MyService.class);
controller.setService(serviceMock);

edited Nov 21, 2013 at 7:40

answered Nov 20, 2013 at 18:02

Stefan Birkner

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2 Comments

Arun Over a year ago

Thanks @StefanBirkner. Problem solved. FYI : you need to pass MyService.class in mock(..) . BTWN Ive used @RunWith(MockitoJUnitRunner.class) to initialze mock objects.. code is much cleaner.

Pieter De Bie Over a year ago

With it's clean api and features like this it baffles me that Mockito isn't the de facto standard for mocking in java.

lkamal · Accepted Answer · 2013-11-20 17:50:13Z

1

If a class in controller uses a service class, you can mock the service class an inject into the controller class when you are unit testing the controller class.

public class MyController {
    private MyService myService;

    public void setMyService(MyService myService) {
        this.myservice = myservice;
    }
}

Whether you mock an interface or a class depends on the reference type that the controller class has.

In above example, if MyService is an interface you can mock that interface. But if it is a class, then you have to mock that class.

Hope that resolves your concern.

answered Nov 20, 2013 at 17:50

lkamal

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