void load() {
    fetchData().subscribeOn(getIoScheduler())
            .observeOn(getMainThreadScheduler())
            .doOnError(throwable -> System.out.println("doOnError " + throwable))
            .subscribe(new Subscriber<MyObject>() {
                @Override
                public void onCompleted() {
                    System.out.println("onCompleted");
                }

                @Override
                public void onError(Throwable e) {
                    System.out.println("onError " + e);
                    handleError();
                }

                @Override
                public void onNext(MyObject myObject) {
                    handleSuccess(myObject);
                }
            });
 }

@Test
public void load() {
        Mockito.doReturn(Schedulers.immediate())
                .when(presenter)
                .getMainThreadScheduler();
        Mockito.doReturn(Schedulers.immediate())
                .when(presenter)
                .getIoScheduler();

        // a) Success case
MyObject object = Mockito.mock(MyObject.class);
        Mockito.doReturn(Observable.just(object))
                .when(presenter)
                .fetchData();

        presenter.load();

        Mockito.verify(presenter)
                .fetchData();
        Mockito.verify(presenter)
                .handleSuccess(object);
        Mockito.reset(presenter);

        // b) Error case
        Mockito.doReturn(Observable.error(new Exception("dummy exception"))).when(presenter)
                .fetchData();

        presenter.load();

        Mockito.verify(presenter)
                .handleError();
}

@Test
    public void load() {
            Mockito.doReturn(Schedulers.immediate())
                    .when(presenter)
                    .getMainThreadScheduler();
            Mockito.doReturn(Schedulers.immediate())
                    .when(presenter)
                    .getIoScheduler();

            // b) Error case
            Mockito.doReturn(Observable.error(new Exception("dummy exception"))).when(presenter)
                    .fetchData();

            presenter.load();

            Mockito.verify(presenter)
                    .handleError();
    }

onError