// 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> where(bool test(T event))
/// Creates a new stream from this stream that discards some data events.
/// The new stream sends the same error and done events as this stream, but it only
/// sends the data events that satisfy the test. 
/// @description Checks that all stream events are checked by the test.
/// Checks that the stream sends only the data events that satisfy the test.
/// @author kaigorodov

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

void check(Iterable data, bool test(int element)) {
  Stream s = IsolateStream.fromIterable(data);
  List collected = [];
  bool _test(element) {
    if (test(element)) {
      return true;
    } else {
      collected.add(element);
      return false;
    }
  }

  asyncStart();
  Stream sw = s.where(_test);
  sw.listen((var value) {
    Expect.isTrue(test(value));
    collected.add(value);
  }, onDone: () {
    Expect.setEquals(data, collected);
    asyncEnd();
  });
}

main() {
  check([1, 2, 3, 4], (int element) => element == 4);
  check([1, 2, 3], (int element) => element > 2);
  check(new Iterable.generate(10, (int index) => index * 5),
      (int? element) => element == 30);
}