|  | // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file | 
|  | // for details. All rights reserved. Use of this source code is governed by a | 
|  | // BSD-style license that can be found in the LICENSE file. | 
|  |  | 
|  | import "dart:async"; | 
|  | import "package:expect/expect.dart"; | 
|  | import "package:async_helper/async_helper.dart"; | 
|  |  | 
|  | expectList(stream, list) { | 
|  | return stream.toList().then((v) { | 
|  | Expect.listEquals(v, list); | 
|  | }); | 
|  | } | 
|  |  | 
|  | Stream makeStream(int n) async* { | 
|  | for (int i = 0; i < n; i++) yield i; | 
|  | } | 
|  |  | 
|  | main() { | 
|  | fivePartialSums(Stream s) async* { | 
|  | var r = 0; | 
|  | await for (var v in s.take(5)) yield r += v; | 
|  | } | 
|  |  | 
|  | asyncStart(); | 
|  | expectList(fivePartialSums(makeStream(10)), [0, 1, 3, 6, 10]) | 
|  | .then(asyncSuccess); | 
|  | } |