How to test RxJava chain single emission

rxjava-testing.md

Given the following SomePresenter/ SomeViewModel.java

void someAction(){
  subscription = someObservable()
                    .subscribeOn(getBgThread())
                    .compose(screenProgressDialog.bindLoading())
                    .observeOn(getUiThread())
                    .subscribe(new Subscriber<GetDailyHistoryEvent>() {
                        @Override
                        public void onCompleted() {

                        }

                        @Override
                        public void onError(Throwable e) {
                            Timber.e(e);
                            screenToast.show(R.string.error_generic_server_message, Toast.LENGTH_SHORT);
                        }

                        @Override
                        public void onNext(GetDailyHistoryEvent someObject) {
                            updateUI(someObject);
                        }
                    });
}

Then the test:

@Before
public void setup() {
  Mockito.doReturn(testScheduler).when(viewModel).getBgThread();
  Mockito.doReturn(Schedulers.immediate()).when(viewModel).getUiThread();
  Mockito.doReturn(RxTestUtils.newDummyComposeTransformer())
                .when(screenProgressDialog)
                .bindLoading();
}

@Test
    public void test_fetchBookingDetails_woCache() {
        BookingDetail bookingDetail = BookingDetail.builder()
                .forTest()
                .build();
        GetDailyHistoryEvent.DailyHistory dailyHistory = GetDailyHistoryEvent.DailyHistory.create("dafwe", null, Collections
                .singletonList(bookingDetail), 1, true);
        GetDailyHistoryEvent getDailyHistoryEvent = GetDailyHistoryEvent.create(Collections.singletonList(dailyHistory));
        viewModel.timeCreated = bookingDetail.getCreatedTime();
        viewModel.cachedData.clear();// force fetch from remote
        Mockito.doReturn(Observable.just(getDailyHistoryEvent))
                .when(historyRepository)
                .sendGetDailyHistory(Mockito.anyString());
        Mockito.doNothing()
                .when(viewModel)
                .updateUI(getDailyHistoryEvent);

        viewModel.fetchBookingDetails();
        testScheduler.triggerActions();

        Mockito.verify(viewModel)
                .updateUI(getDailyHistoryEvent);
    }

    @Test
    public void test_fetchBookingDetails_woCache_Error() {
        viewModel.timeCreated = "faef;aewfoiawefoia";
        viewModel.cachedData.clear();// force fetch from remote
        Mockito.doReturn(Observable.error(new Exception("something wrong")))
                .when(historyRepository)
                .sendGetDailyHistory(Mockito.anyString());

        viewModel.fetchBookingDetails();
        testScheduler.triggerActions();

        Mockito.verify(viewModel, Mockito.never())
                .updateUI(Mockito.any(GetDailyHistoryEvent.class));
        Mockito.verify(screenToast).show(Mockito.anyInt(), Mockito.anyInt());
    }