@Test
public void mustWorkFromRange() throws Exception {
CompletionStage<List<Integer>> f =
Source.range(0, 10).grouped(20).runWith(Sink.<List<Integer>>head(), materializer);
final List<Integer> result = f.toCompletableFuture().get(3, TimeUnit.SECONDS);
assertEquals(11, result.size());
Integer counter = 0;
for (Integer i : result) assertEquals(i, counter++);
}
