@Test public void testErrorInParentObservable() { TestSubscriber<Integer> ts = new TestSubscriber<>(); Observable.mergeDelayError( Observable.just(Observable.just(1), Observable.just(2)) .startWith(Observable.<Integer>error(new RuntimeException()))) .subscribe(ts); ts.awaitTerminalEvent(); ts.assertTerminated(); ts.assertValues(1, 2); assertEquals(1, ts.errorCount()); }