| // Copyright (c) 2018, 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. |
| |
| // @dart = 2.9 |
| |
| // Test that async/await syntax works for synchronously completed futures. |
| // Such futures are used by Flutter (see http://dartbug.com/32098). |
| |
| import 'dart:async'; |
| |
| import 'package:expect/expect.dart'; |
| import 'package:async_helper/async_helper.dart'; |
| |
| class SynchronousFuture<T> implements Future<T> { |
| final T v; |
| |
| SynchronousFuture(this.v); |
| |
| Future<E> then<E>(FutureOr<E> f(T v), {Function onError}) { |
| final u = f(v); |
| return u is Future<dynamic> |
| ? (u as Future<dynamic>).then((v) => v as E) |
| : new SynchronousFuture<E>(u); |
| } |
| |
| Stream<T> asStream() => throw 'unimplemented'; |
| Future<T> catchError(Function onError, {bool test(dynamic error)}) => |
| throw 'unimplemented'; |
| Future<T> timeout(Duration timeLimit, {dynamic onTimeout()}) => |
| throw 'unimplemented'; |
| Future<T> whenComplete(dynamic action()) => throw 'unimplemented'; |
| } |
| |
| void main() { |
| var stage = 0; |
| asyncTest(() async { |
| int v; |
| Expect.equals(0, stage++); |
| v = await new SynchronousFuture<int>(stage); |
| Expect.equals(1, v); |
| Expect.equals(1, stage++); |
| v = await new SynchronousFuture<int>(stage); |
| Expect.equals(2, v); |
| Expect.equals(2, stage++); |
| v = await new SynchronousFuture<int>(stage); |
| Expect.equals(3, v); |
| Expect.equals(3, stage++); |
| }); |
| } |