@Test public void mustBeAbleToUseSimpleOperators() { final JavaTestKit probe = new JavaTestKit(system); final String[] lookup = {"a", "b", "c", "d", "e", "f"}; final java.lang.Iterable<Integer> input = Arrays.asList(0, 1, 2, 3, 4, 5); final Source<Integer, NotUsed> ints = Source.from(input); ints.drop(2) .take(3) .takeWithin(FiniteDuration.create(10, TimeUnit.SECONDS)) .map(elem -> lookup[elem]) .filter(elem -> !elem.equals("c")) .grouped(2) .mapConcat(elem -> elem) .groupedWithin(100, FiniteDuration.create(50, TimeUnit.MILLISECONDS)) .mapConcat(elem -> elem) .runFold("", (acc, elem) -> acc + elem, materializer) .thenAccept(elem -> probe.getRef().tell(elem, ActorRef.noSender())); probe.expectMsgEquals("de"); }