LibTest/async/Stream/Stream.periodic_A02_t01.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.

// @dart = 2.9

/// @assertion Stream.periodic(Duration period,
///     [T computation(int computationCount)])
/// The event values are computed by invoking computation.
/// @description Checks that event values are computed by invoking computation.
/// @author kaigorodov

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

void check(int periodMs) {
  Stream s = new Stream<int>.periodic(durationMs(periodMs),
          (computationCount) => computationCount * periodMs);
  int count = 0;
  asyncStart();
  StreamSubscription<int> subs;
  subs = s.listen((data) {
    Expect.equals(count * periodMs, data, "check($periodMs): data=$data");
    if (count++ == 10) {
      subs.cancel();
      asyncEnd();
    }
  }) as StreamSubscription<int>;
}

main() {
  check(0);
  check(1);
  check(10);
  check(30);
  check(-10);
}