LanguageFeatures/FinalizationRegistry/Finalizer/attach_A01_t03.dart

// Copyright (c) 2022, 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 void attach(
///    Object value,
///    T finalizationToken,
///    {Object? detach}
/// )
/// Attaches this finalizer to [value].
///
/// When [value] is longer accessible to the program, while still having an
/// attachement to this finalizer, the [callback] of this finalizer may be
/// called with [finalizationToken] as argument.
///
/// @description Checks that generic finalizer can be attached to the different
/// objects and token is passed as a callback function parameter when object
/// becomes inaccessible.
/// @author iarkh@unipro.ru

import "../gc_utils_lib.dart";
import "../../../Utils/expect.dart";

class A {}
Object? returnedToken;
int cnt = 0;

final Finalizer<int> finalizer = Finalizer((token) {
  returnedToken = token;
  cnt++;
});

main() async {
  {
    Object? obj = Object();
    finalizer.attach(obj, 1);
    print(obj);
  }
  await triggerGcWithDelay();
  Expect.equals(1, returnedToken);

  {
    Object? obj = A();
    finalizer.attach(obj, 15);
    print(obj);
    obj = null;
    await triggerGcWithDelay();
    Expect.equals(15, returnedToken);
  }

  {
    Object obj = List.filled(100, 1);
    finalizer.attach(obj, 14);
    print(obj);
    obj = A();
    await triggerGcWithDelay();
    Expect.equals([], returnedToken);
  }

  Expect.equals(3, cnt);
}