| // Copyright (c) 2024, 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. |
| |
| import 'dart:async'; |
| |
| import 'package:async_helper/async_helper.dart'; |
| import 'package:expect/expect.dart'; |
| import 'package:expect/config.dart'; |
| |
| import 'finalizer_test.dart' show invalidObjects, produceGarbage, Foo; |
| |
| main() async { |
| testWeakReferenceArgumentValidation(); |
| |
| // This test doesn't work reliably on the web yet as it's hard to trigger GC |
| // that will run finalizer and weak reference processing. |
| if (isVmConfiguration) { |
| asyncStart(); |
| await testWeakReferenceWeakness(); |
| asyncEnd(); |
| } |
| } |
| |
| void testWeakReferenceArgumentValidation() { |
| final foo = Foo(); |
| final weakRef = WeakReference(foo); |
| Expect.equals(weakRef.target, foo); |
| |
| for (final invalid in invalidObjects) { |
| Expect.throws(() => WeakReference(invalid)); |
| } |
| } |
| |
| Future testWeakReferenceWeakness() async { |
| late final WeakReference<Foo> weakReference; |
| { |
| Foo? foo = Foo(); |
| weakReference = WeakReference<Foo>(foo); |
| Expect.equals(weakReference.target, foo); |
| foo = null; |
| } |
| asyncStart(); |
| // According to the WeakReference specification: |
| // |
| // There are no guarantees that a weak reference will ever be cleared |
| // even if all references to its target are weak references. |
| // |
| // Wait a few iterations and give up if target is not cleared. |
| const int numIterations = 10; |
| int i = 0; |
| for (; weakReference.target != null && i < numIterations; ++i) { |
| produceGarbage(); |
| await Future.delayed(const Duration(milliseconds: 10)); |
| } |
| Expect.isTrue(i == numIterations || weakReference.target == null); |
| asyncEnd(); |
| } |