public void InsertBeforeTest(int beforeItemIndex, int originTargetIndex, int changedItemsCount)
{
var beforeItem = _collection[beforeItemIndex];
var newItem = new SortObj("E");
_collection.InsertBefore(beforeItem, newItem);
var changedItems = _collection.FlushModifications();
Assert.AreEqual(originTargetIndex, _collection.IndexOf(beforeItem));
Assert.AreEqual(changedItemsCount, changedItems.Count);
Assert.IsTrue(changedItems.Contains(newItem));
}
