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// Copyright (c) 2015, 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
// Test empty stream.
import "package:expect/expect.dart";
import "dart:async";
import 'package:async_helper/async_helper.dart';
main() {
asyncStart();
runTest().whenComplete(asyncEnd);
}
Future runTest() async {
unreachable([a, b]) {
throw "UNREACHABLE";
}
int tick = 0;
ticker() {
tick++;
}
asyncStart();
Stream<int> s = const Stream<int>.empty(); // Is const constructor.
Expect.isFalse(s is Stream<String>); // Respects type parameter.
StreamSubscription<int> sub =
s.listen(unreachable, onError: unreachable, onDone: ticker);
Expect.isFalse(sub is StreamSubscription<String>); // Type parameter in sub.
// Doesn't do callback in response to listen.
Expect.equals(tick, 0);
await flushMicrotasks();
// Completes eventually.
Expect.equals(tick, 1);
// It's a broadcast stream - can listen twice.
Expect.isTrue(s.isBroadcast);
StreamSubscription<int> sub2 =
s.listen(unreachable, onError: unreachable, onDone: unreachable);
// respects pause.
sub2.pause();
await flushMicrotasks();
// respects cancel.
sub2.cancel();
await flushMicrotasks();
Expect.equals(tick, 1);
// Still not complete.
StreamSubscription<int> sub3 =
s.listen(unreachable, onError: unreachable, onDone: ticker);
// respects pause.
sub3.pause();
Expect.equals(tick, 1);
await flushMicrotasks();
// Doesn't complete while paused.
Expect.equals(tick, 1);
sub3.resume();
await flushMicrotasks();
// Now completed.
Expect.equals(tick, 2);
asyncEnd();
}
Future flushMicrotasks() => new Future.delayed(Duration.zero);