@Test
public void asyncActionSingleErrors() {

    AmazonWebServiceRequest someRequest = AmazonWebServiceRequest.NOOP;
    final MockAsyncClient<AmazonWebServiceRequest, String> client = new MockAsyncClient<>(someRequest, "some response");
    RuntimeException exception = new RuntimeException("error when initiating an async operation");
    final Single<String> completable = AwsObservableExt.asyncActionSingle(supplier -> client.throwException(exception));
    TestScheduler testScheduler = Schedulers.test();
    final AssertableSubscriber<String> subscriber = completable.subscribeOn(testScheduler).test();
    testScheduler.triggerActions();
    subscriber.assertError(exception);
}