@Test(groups = "standalone")
  public void testToObservableError() {
    final TestSubscriber<Response> tester = new TestSubscriber<>();

    try (AsyncHttpClient client = asyncHttpClient()) {
      Observable<Response> o1 =
          AsyncHttpObservable.toObservable(() -> client.prepareGet("http://gatling.io/ttfn"));
      o1.subscribe(tester);
      tester.awaitTerminalEvent();
      tester.assertTerminalEvent();
      tester.assertCompleted();
      tester.assertNoErrors();
      List<Response> responses = tester.getOnNextEvents();
      assertNotNull(responses);
      assertEquals(responses.size(), 1);
      assertEquals(responses.get(0).getStatusCode(), 404);
    } catch (Exception e) {
      Thread.currentThread().interrupt();
    }
  }