| // 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 Stream<T> distinct([bool equals(T previous, T next)]) |
| /// Skips data events if they are equal to the previous data event. |
| /// The returned stream provides the same events as this stream, |
| /// except that it never provides two consequtive data events that are equal. |
| /// Equality is determined by the provided equals method. |
| /// If that is omitted, the '==' operator on the last provided data element is used. |
| /// @description Checks that if parameter is omitted, returned stream does not contain |
| /// consecutive equal elements in terms of operator ==. |
| /// @author kaigorodov |
| |
| import "dart:async"; |
| import "../../../Utils/expect.dart"; |
| import "IsolateStream.dart" as IsolateStream; |
| |
| check(Iterable<int?> data) { |
| Stream s = IsolateStream.fromIterable(data); |
| Stream d = s.distinct(); |
| bool first = true; |
| var previous; |
| asyncStart(); |
| d.listen((var event) { |
| if (first) { |
| first = false; |
| } else { |
| Expect.isFalse(previous == event); |
| } |
| previous = event; |
| }, onDone: () { |
| asyncEnd(); |
| }); |
| } |
| |
| main() { |
| check([]); |
| check([1, 2, 2, 3]); |
| check([1, 2, null, null]); |
| check(new Iterable.generate(0, (int index) => 1)); |
| } |