LibTest/async/Stream/asBroadcastStream_A01_t04.test.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 Stream<T> asBroadcastStream (
///   {void onListen(StreamSubscription<T> subscription),
///    void onCancel(StreamSubscription<T> subscription)})
/// Returns a multi-subscription stream that produces the same events as this.
///
/// The returned stream will subscribe to this stream when its first subscriber
/// is added, and will stay subscribed until this stream ends, or a callback
/// cancels the subscription.
///
/// @description Checks that if some subscriptions to broadcast stream cancel,
/// other still listen to completion.
/// @author ilya

library asBroadcastStream_A01_t04;

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

const int subscribersCount = 10;
const int dataSize = 1000;

void multiListen(Stream<int> s) {
  for (int i = 0; i < subscribersCount; ++i) {
    asyncStart();
    if (i.isEven) {
      // listener that quits after half of data
      var quitter;
      quitter = s.listen((int data) {
        if (data > dataSize / 2) {
          quitter.cancel();
          asyncEnd();
        }
      });
    } else {
      // listener that works to completion
      int processed = 0;
      s.listen((int data) {
        ++processed;
      }, onDone: () {
        Expect.equals(dataSize, processed);
        asyncEnd();
      });
    }
  }
}

void test(CreateStreamFunction create) {
  multiListen(create(new Iterable<int>.generate(dataSize, (i) => i))
      .asBroadcastStream());
}