LibTest/async/StreamController/hasListener_A01_t02.dart

// 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 bool hasListener
/// Whether there is a subscriber on the Stream.
/// @description Checks that the property returns correct value.
/// A broadcast stream is checked.
/// @author kaigorodov

import "dart:async";
import "../../../Utils/expect.dart";

main() {
  StreamController controller = new StreamController.broadcast();
  Stream s = controller.stream;
  Expect.isFalse(controller.hasListener);

  List events1 = new List.empty(growable: true);
  StreamSubscription ss1 = s.listen((event) {events1.add(event);});
  Expect.isTrue(controller.hasListener);

  StreamSubscription ss2 = s.listen((event) {events1.add(event);});
  Expect.isTrue(controller.hasListener);

  ss1.cancel();
  Expect.isTrue(controller.hasListener);

  ss2.cancel();
  Expect.isFalse(controller.hasListener);

  ss2 = s.listen((event){events1.add(event);});
  Expect.isTrue(controller.hasListener);

  ss2.cancel();
  Expect.isFalse(controller.hasListener);

  controller.close();
}