| // 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. |
| |
| // @dart = 2.9 |
| |
| /// @assertion final E first |
| /// Throws a StateError if this is empty. Otherwise returns the first element in |
| /// the iteration order, equivalent to this.elementAt(0). |
| /// @description Checks that a StateError is thrown if queue is empty. |
| /// @author kaigorodov |
| |
| import "../../../Utils/expect.dart"; |
| import "dart:collection"; |
| |
| main() { |
| DoubleLinkedQueue queue = new DoubleLinkedQueue(); |
| |
| Expect.throws(() { queue.first; }, (e) => e is StateError); |
| |
| queue.addFirst(1); |
| queue.addFirst(2); |
| queue.clear(); |
| |
| Expect.throws(() { queue.first; }, (e) => e is StateError); |
| } |