### Question:
TakeWhileStageFactory implements ProcessingStageFactory<Stage.TakeWhile> { @SuppressWarnings("unchecked") @Override public <I, O> ProcessingStage<I, O> create(Engine engine, Stage.TakeWhile stage) { Predicate<I> predicate = (Predicate<I>) Objects.requireNonNull(stage.getPredicate()); return source -> (Multi<O>) source.transform().byTakingItemsWhile(predicate); }  @SuppressWarnings("unchecked") @Override ProcessingStage<I, O> create(Engine engine, Stage.TakeWhile stage);  }### Answer:
@Test public void create() throws ExecutionException, InterruptedException { Multi<Integer> publisher = Multi.createFrom().items(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) .emitOn(executor); List<Integer> list = ReactiveStreams.fromPublisher(publisher).takeWhile(i -> i < 6).toList().run() .toCompletableFuture().get(); assertThat(list).hasSize(5).containsExactly(1, 2, 3, 4, 5); }
@SuppressWarnings("ConstantConditions") @Test public void createWithoutStage() { assertThrows(NullPointerException.class, () -> factory.create(null, null)); }
@Test public void createWithoutPredicate() { assertThrows(NullPointerException.class, () -> factory.create(null, () -> null)); }