[FIXED] Mock final method in superclass

Issue

I am creating a new service 'MyService' that extends AbstractScheduledService and MyService inherits a final method isRunning() from it.

public class MyService extends AbstractScheduledService {}

I also have a health check for 'MyService' that invokes isRunning() to see if 'MyService' is healthy.

public class MyServiceHealthcheck {
       MyService myService;
       
       @Inject
       public MyServiceHealthCheck(MyService myService) {
          this.myService = myService;
       }

       public boolean isHealthy() {
          return myService.isRunning();
       }
}

And finally, I am trying to create unit test 'MyServiceHealthcheckTest' for testing MyServiceHealthcheck

public class MyServiceHealthcheckTest {
       @Mock MyService myService;
}

The mock is initialized properly and I'm able to get expected value for methods defined in MyService but myService.isRunning() always returns a NullPointerException. What is the best way to mock isRunning() method?

Solution

You need to configure Mockito so that mocking final classes and methods is possible. To achieve this you need to add a text file named org.mockito.plugins.MockMaker to your project src/test/resources/mockito-extensions directory. It should include a single line of text as follows: mock-maker-inline.

Answered By - João Dias
Answer Checked By - Timothy Miller (JavaFixing Admin)