LibTest/async/Stream/asBroadcastStream_A03_t01.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.
///
/// If onListen is provided, it is called with a subscription-like object that
/// represents the underlying subscription to this stream. It is possible to
/// pause, resume or cancel the subscription during the call to onListen. It
/// is not possible to change the event handlers, including using
/// StreamSubscription.asFuture.
///
/// @description Checks that onListen callback is called when broadcast stream
/// gets its subscribers and if subscription to underlying stream is cancelled
/// in this callback, no onData events will be fired.
/// @author ilya

library asBroadcastStream_A03_t01;
import "dart:async";
import "../../../Utils/expect.dart";

void test(CreateStreamFunction create) {
  Stream<int> s = create([1,2,3,4,5]);

  asyncStart();

  Stream<int> b = s.asBroadcastStream(onListen: (StreamSubscription ss) {
    ss.cancel();
    asyncEnd();
  });

  b.listen((_) {
    Expect.fail('unexpected onData event');
  });

  b.listen((_) {
    Expect.fail('unexpected onData event');
  });
}