Public Sub Tick() 

public void Tick()

WeakReference r;
ObjectKeepAlive keep = new ObjectKeepAlive(1, 10, TimeSpan.FromTicks(1), true);

for (int i = 0; i < 35; i++)
    keep.Add(i);

if (true)
{
    object target = new MyObject();
    r = new WeakReference(target);
    keep.Add(target);
    target = null;
}

_destroyed = false;
Assert.IsTrue(r.IsAlive);

for (int i = 0; i < 100; i++)
    keep.Tick();

Assert.IsTrue(r.IsAlive);

GC.GetTotalMemory(true);
GC.WaitForPendingFinalizers();
Assert.IsTrue(r.IsAlive);
Assert.IsFalse(_destroyed);

System.Threading.Thread.Sleep(1);

GC.GetTotalMemory(true);
GC.WaitForPendingFinalizers();
Assert.IsTrue(r.IsAlive);
Assert.IsFalse(_destroyed);

keep.Clear();

GC.GetTotalMemory(true);
GC.WaitForPendingFinalizers();
Assert.IsFalse(r.IsAlive);
Assert.IsTrue(_destroyed);

Dim r As WeakReference
Dim keep As New ObjectKeepAlive(1, 10, TimeSpan.FromTicks(1), True)

Dim i As Integer = 0
While i < 35
    keep.Add(i)
    System.Math.Max(System.Threading.Interlocked.Increment(i),i - 1)
End While

If True Then
    Dim target As Object = New MyObject()
    r = New WeakReference(target)
    keep.Add(target)
    target = Nothing
End If

_destroyed = False
Assert.IsTrue(r.IsAlive)

Dim i As Integer = 0
While i < 100
    keep.Tick()
    System.Math.Max(System.Threading.Interlocked.Increment(i),i - 1)
End While

Assert.IsTrue(r.IsAlive)

GC.GetTotalMemory(True)
GC.WaitForPendingFinalizers()
Assert.IsTrue(r.IsAlive)
Assert.IsFalse(_destroyed)

System.Threading.Thread.Sleep(1)

GC.GetTotalMemory(True)
GC.WaitForPendingFinalizers()
Assert.IsTrue(r.IsAlive)
Assert.IsFalse(_destroyed)

keep.Clear()

GC.GetTotalMemory(True)
GC.WaitForPendingFinalizers()
Assert.IsFalse(r.IsAlive)
Assert.IsTrue(_destroyed)