public void OneCollectionOneItemTest()
{
var c = new CollectionViewModel();
var i = new ItemViewModel();
Assert.AreEqual(null, i.Collection);
Assert.AreEqual(0, c.Count);
i.Collection = c;
Assert.AreEqual(c, i.Collection);
Assert.AreEqual(1, c.Count);
i.Collection = null;
Assert.AreEqual(null, i.Collection);
Assert.AreEqual(0, c.Count);
c.Add(i);
Assert.AreEqual(c, i.Collection);
Assert.AreEqual(1, c.Count);
c.Remove(i);
Assert.AreEqual(null, i.Collection);
Assert.AreEqual(0, c.Count);
}