| // Copyright (c) 2016, 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. |
| |
| /** |
| * @assertion If f is marked async*, then a fresh instance s implementing |
| * the built-in class Stream is associated with the invocation and |
| * immediately returned. When s is listened to, execution of the body of f will |
| * begin. When f terminates: |
| * • If the current return value is defined then, if s has been canceled |
| * then its cancellation future is completed with null. |
| * • If the current exception x is defined: |
| * – x is added to s. |
| * – If s has been canceled then its cancellation future is completed with |
| * x as an error. |
| * • s is closed. |
| * |
| * @description Check that if the current return value is defined then, if s |
| * has been canceled then its cancellation future is completed with null. |
| * |
| * @author a.semenov@unipro.ru |
| */ |
| import 'dart:async'; |
| import '../../../Utils/expect.dart'; |
| |
| int sum = 0; |
| |
| Stream generator() async* { |
| // do not use yield here, because it may terminate the function |
| // without defining current return value, just do some actions |
| for (int i = 0; i < 10000; i++) { |
| sum += i; |
| } |
| } |
| |
| main() { |
| asyncStart(); |
| Stream stream = generator(); |
| Future cancelFuture = stream.listen((_) {}).cancel(); |
| cancelFuture.then((v) { |
| // make sure the generator function has finished |
| Expect.equals(49995000, sum); |
| Expect.isNull(v); |
| asyncEnd(); |
| }); |
| } |