| // Copyright 2018 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| import 'context.dart'; |
| |
| /// The current system clock instance. |
| SystemClock get systemClock => context.get<SystemClock>(); |
| |
| /// A class for making time based operations testable. |
| class SystemClock { |
| /// A const constructor to allow subclasses to be const. |
| const SystemClock(); |
| |
| /// Create a clock with a fixed current time. |
| const factory SystemClock.fixed(DateTime time) = _FixedTimeClock; |
| |
| /// Retrieve the current time. |
| DateTime now() => DateTime.now(); |
| |
| /// Compute the time a given duration ago. |
| DateTime ago(Duration duration) { |
| return now().subtract(duration); |
| } |
| } |
| |
| class _FixedTimeClock extends SystemClock { |
| const _FixedTimeClock(this._fixedTime); |
| |
| final DateTime _fixedTime; |
| |
| @override |
| DateTime now() => _fixedTime; |
| } |
