mono/mcs/class/System.ComponentModel.Composition/Tests/UnitTestFramework/System/ReferenceTracker.cs

// -----------------------------------------------------------------------
// Copyright (c) Microsoft Corporation.  All rights reserved.
// -----------------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.Linq;
using System.UnitTesting;

namespace System
{
    public class ReferenceTracker
    {
        public readonly List<WeakReference> ReferencesExpectedToBeCollected = new List<WeakReference>();
        public readonly List<WeakReference> ReferencesNotExpectedToBeCollected = new List<WeakReference>();

        public void AddReferencesExpectedToBeCollected(params object[] objects)
        {
            for (int i = 0; i < objects.Length; i++)
            {
                ReferencesExpectedToBeCollected.Add(new WeakReference(objects[i]));
                objects[i] = null;
            }
        }

        public void AddReferencesNotExpectedToBeCollected(params object[] objects)
        {
            for (int i = 0; i < objects.Length; i++)
            {
                ReferencesNotExpectedToBeCollected.Add(new WeakReference(objects[i]));
                objects[i] = null;
            }
        }

        public void CollectAndAssert()
        {
            GC.Collect();
            GC.WaitForPendingFinalizers();

            EnumerableAssert.IsTrueForAll(ReferencesExpectedToBeCollected, wr => wr.Target == null, "Object should have been collected.");
            EnumerableAssert.IsTrueForAll(ReferencesNotExpectedToBeCollected, wr => wr.Target != null, "Object should be have NOT been collected.");
        }
    }
}