public void CollectionChangedTest()
{
var s = new Subject <CollectionChanged <int> >();
var target = s.ToReadOnlyReactiveCollection();
target.Count.Is(0);
s.OnNext(CollectionChanged <int> .Add(0, 10));
s.OnNext(CollectionChanged <int> .Add(1, 2));
target.Is(10, 2);
s.OnNext(CollectionChanged <int> .Remove(0));
target.Is(2);
s.OnNext(CollectionChanged <int> .Add(1, 3));
target.Is(2, 3);
s.OnNext(CollectionChanged <int> .Replace(1, 100));
target.Is(2, 100);
s.OnNext(CollectionChanged <int> .Reset);
target.Count.Is(0);
}