@Test public void reduceForJavaApiMustWork() throws Exception { LinkedList<Future<String>> listFutures = new LinkedList<Future<String>>(); StringBuilder expected = new StringBuilder(); for (int i = 0; i < 10; i++) { expected.append("test"); listFutures.add( Futures.future( new Callable<String>() { public String call() { return "test"; } }, system.dispatcher())); } Future<String> result = Futures.reduce( listFutures, new Function2<String, String, String>() { public String apply(String r, String t) { return r + t; } }, system.dispatcher()); assertEquals(Await.result(result, timeout), expected.toString()); }