LibTest/async/Stream/expand_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<S> expand<S>(Iterable<S> convert(T value))
/// If a broadcast stream is listened to more than once, each subscription will
/// individually call convert and expand the events.
/// @description Checks that [convert] is called once per event per subscription.
/// @author a.semenov@unipro.ru

library expand_A03_t01;

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

void check<T>(Stream<T> s, List<T> expected) {
  Map<T, int> convertLog = new Map();
  asyncStart();
  Stream<T> stream = s.asBroadcastStream().expand((T event) {
    convertLog[event] = 1 + convertLog.putIfAbsent(event, () => 0);
    return [event];
  });
  Future.wait([stream.toList(), stream.toList(), stream.toList()])
      .then((List<List<T>> results) {
    Expect.equals(3, results.length);
    results.forEach((actual) => Expect.listEquals(expected, actual));
    Expect.equals(expected.length, convertLog.length);
    expected.forEach((e) => Expect.equals(3, convertLog[e]));
    asyncEnd();
  });
}

void test(CreateStreamFunction create) {
  check(create([]), []);
  check(create([1, 2, 3, 4, 5]), [1, 2, 3, 4, 5]);
  check(create(["a", "b", "c"]), ["a", "b", "c"]);
}