Mock a method on extended class without super()

/* special thanks to
 * https://stackoverflow.com/questions/3467801/mockito-how-to-mock-only-the-call-of-a-method-of-the-superclass
 * I did a few editions
 *
 * The method validate()in BaseService is never called during tests
 */


class BaseService {

    public void validate() {
        throw new IllegalArgumentException(" I must not be called");
    }

    public void save() {
        // Save method of super will still be called.
        validate();
    }
}

class ChildService extends BaseService {

    public void load() {
    }

    public void save() {
        load();
    }
}

@RunWith(MockitoJUnitRunner.class)
public class TrainMlpScheduleSoftSensorService0Test {

    @Test
    public void testSave() {
        ChildService spy = Mockito.spy(new ChildService());

        // Prevent/stub logic in super.save()
        Mockito.doNothing().when((BaseService) spy).validate();

        // When
        spy.validate();
    }
}