blob: ff5dec1d9ff66036a048ad9db0b0c9dc3ac1f7a6 [file] [log] [blame]
// Copyright (c) 2019, 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
import 'dart:async';
import "package:expect/expect.dart";
import "package:async_helper/async_helper.dart";
void main() async {
asyncStart();
{
// There is a first element.
var stream = Stream<int>.value(42);
var first = await stream.first;
Expect.equals(42, first);
// Is single-subscription.
Expect.throws(() => stream.first);
}
{
// There is no second element.
var stream = Stream<int>.value(42);
try {
await stream.skip(1).first;
Expect.fail("didn't throw");
} on Error {
// Success.
}
}
{
// There is still no second element.
var stream = Stream<int>.value(42);
try {
await stream.elementAt(1);
Expect.fail("didn't throw");
} on Error {
// Success.
}
}
{
// Works with await for.
var stream = Stream<int>.value(42);
var value = null;
await for (value in stream) {}
Expect.equals(42, value);
}
{
// Works with subscriptions and pause-resume.
var stream = Stream<int>.value(42);
var value;
var onDone = Completer();
var sub = stream.listen((v) {
value = v;
}, onDone: () {
Expect.equals(42, value);
onDone.complete();
});
sub.pause();
await Future.delayed(Duration(milliseconds: 10));
Expect.isNull(value);
Expect.isFalse(onDone.isCompleted);
sub.resume();
await onDone.future;
}
asyncEnd();
}