| // Copyright (c) 2011, 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 DoubleLinkedQueueEntry<E> firstEntry() |
| /// @description Checks that null is returned if this queue is empty. |
| /// @note undocumented |
| /// @author kaigorodov |
| |
| import "../../../Utils/expect.dart"; |
| import "dart:collection"; |
| |
| main() { |
| DoubleLinkedQueue queue = new DoubleLinkedQueue(); |
| |
| Expect.isNull(queue.firstEntry()); |
| |
| queue.addFirst(1); |
| queue.addFirst(2); |
| queue.clear(); |
| |
| Expect.isNull(queue.firstEntry()); |
| } |