Fixed test for create filter property

gistfile1.txt

[Test]
public async Task TestFilterOnProperty()
{
    var listA = new SourceList<X>();
    var listB = new SourceList<X>();

    using (IObservableList<X> list = listA.Connect()
					.Or(listB.Connect())
					.AsObservableList())
    {
	var nameA1 = "A1";
	var a1 = new X(nameA1);
	var a2 = new X("A2");
	listA.Edit(l =>
	{
	    l.Clear();
	    l.Add(a1);
	    l.Add(a2);
	});

	var b1 = new X("B1");
	var b2 = new X("B2");
	listB.Edit(l =>
	{
	    l.Clear();
	    l.Add(b1);
	    l.Add(b2);
	});

	Assert.AreEqual(4, list.Count);

	int count = await list.CountChanged.FirstAsync();

	Assert.AreEqual(4, count);

	IObservable<IChangeSet<X>> obsFiltered = list.Connect()
	    .FilterOnProperty(v => v.IsConnected, v => v.IsConnected);

	using (IObservableList<X> obsFilteredAsList = obsFiltered.AsObservableList())
	{
	    IObservable<IChangeSet<XVm>> obsTransformed = obsFiltered
		.Transform(v => new XVm(v))
		.DisposeMany();

	    var ctorCount = 0;
	    var dtorCount = 0;
	    using (IObservableList<XVm> obsTransformedAsList = obsTransformed.AsObservableList())
	    {
		ctorCount += 4;

		Assert.That(obsFilteredAsList.Items.Contains(a1));
		Assert.That(obsFilteredAsList.Items.Count(), Is.EqualTo(obsTransformedAsList.Items.Count()));

		a1.IsConnected = false;
		Assert.That(obsFilteredAsList.Items, Has.No.Member(a1));
		dtorCount++;
		Assert.That(XVm.Constructed, Is.EqualTo(ctorCount));
		Assert.That(XVm.Destructed, Is.EqualTo(dtorCount));

		a1.IsConnected = true;
		Assert.That(obsFilteredAsList.Items, Has.Member(a1));
		ctorCount++;
		Assert.That(XVm.Constructed, Is.EqualTo(ctorCount));
		Assert.That(XVm.Destructed, Is.EqualTo(dtorCount));

		Console.WriteLine("--remove");
		listA.Remove(a1);
		dtorCount++;
		Assert.That(XVm.Constructed, Is.EqualTo(ctorCount));
		Assert.That(XVm.Destructed, Is.EqualTo(dtorCount));

		Console.WriteLine("--add");
		listA.Add(a1);
		ctorCount++;
		Assert.That(XVm.Constructed, Is.EqualTo(ctorCount));
		Assert.That(XVm.Destructed, Is.EqualTo(dtorCount));

		Console.WriteLine("--clear");
		listA.Clear();
		dtorCount += 2; //FIX:  List A contains 2 items (was adding 4)
		Assert.That(XVm.Constructed, Is.EqualTo(ctorCount));
		Assert.That(XVm.Destructed, Is.EqualTo(dtorCount));

		Console.WriteLine("--add");

		//FIX: Maybe a debate required!  List B already contains b1, so not regarded as a new item in the Or result
		Debug.Assert(listB.Items.Contains(b1));
		listA.Add(b1); 
	      //  ctorCount++;
		Assert.That(XVm.Constructed, Is.EqualTo(ctorCount));
		Assert.That(XVm.Destructed, Is.EqualTo(dtorCount));

		Console.WriteLine("--disp");
	    }
	    dtorCount +=2; //FIX: Should be +2 as this is the count of the Or derived list 
	    Assert.That(XVm.Constructed, Is.EqualTo(ctorCount));
	    Assert.That(XVm.Destructed, Is.EqualTo(dtorCount));
	}
    }
}