public void MovingItemsIntoCollectionManuallyThrows()
    {
        var source = new Subject<Thing>();
        var col = new TrackingCollection<Thing>(source) { ProcessingDelay = TimeSpan.Zero };
        var count = 0;
        var expectedCount = 2;
        var evt = new ManualResetEvent(false);

        col.Subscribe(t =>
        {
            if (++count == expectedCount)
                evt.Set();
        }, () => { });

        Add(source, GetThing(1, 1));
        Add(source, GetThing(2, 2));
        evt.WaitOne();
        evt.Reset();
        Assert.Throws<InvalidOperationException>(() => col.Move(0, 1));
        col.Dispose();
    }