| // 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 final E single |
| /// Returns the single element in this. |
| /// @description Checks that the method returns the single element of the queue. |
| /// Checks that if this is empty or has more than one element throws a StateError. |
| /// @author kaigorodov |
| |
| import "dart:collection"; |
| import "../../../Utils/expect.dart"; |
| |
| main() { |
| DoubleLinkedQueue queue = new DoubleLinkedQueue(); |
| |
| Expect.throws(() { queue.single; }, (e) => e is StateError); |
| |
| queue.addFirst(1); |
| Expect.isTrue(queue.first == 1); |
| |
| queue.addLast(2); |
| Expect.throws(() { queue.single; }, (e) => e is StateError); |
| } |