How do I unit test a finalizer?

I have the following class which is a decorator for an `IDisposable` object (I have omitted the stuff it adds) which itself implements `IDisposable` using a common pattern: ``` public class DisposableDecorator : IDisposable { private readonly IDisposable _innerDisposable; public DisposableDecorator(IDisposable innerDisposable) { _innerDisposable = innerDisposable; } #region IDisposable Members public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } #endregion ~DisposableDecorator() { Dispose(false); } protected virtual void Dispose(bool disposing) { if (disposing) _innerDisposable.Dispose(); } } ``` I can easily test that `innerDisposable` is disposed when `Dispose()` is called: ``` [Test] public void Dispose__DisposesInnerDisposable() { var mockInnerDisposable = new Mock<IDisposable>(); new DisposableDecorator(mockInnerDisposable.Object).Dispose(); mockInnerDisposable.Verify(x => x.Dispose()); } ``` But how do I write a test to make sure `innerDisposable` does not get disposed by the finalizer? I want to write something like this but it fails, presumably because the finalizer hasn't been called by the GC thread: ``` [Test] public void Finalizer__DoesNotDisposeInnerDisposable() { var mockInnerDisposable = new Mock<IDisposable>(); new DisposableDecorator(mockInnerDisposable.Object); GC.Collect(); mockInnerDisposable.Verify(x => x.Dispose(), Times.Never()); } ```