@Test
public void testFromWithDelaySingle() {

    final List<Observable<Object>> chunks = Collections.singletonList(Observable.just(A));
    Observable<Object> observable = ObservableExt.fromWithDelay(chunks, DELAY_MS, TimeUnit.MILLISECONDS, testScheduler);
    observable = observable.defaultIfEmpty(B);
    observable.subscribe(testSubscriber);
    assertThat(testSubscriber.takeNext()).isSameAs(A);
    assertThat(testSubscriber.takeNext()).isNull();
}