public void BeginUpdateEndUpdate()
{
var dl = new List <TestItemDM> {
new TestItemDM(0), new TestItemDM(1), new TestItemDM(2)
};
var bl = new ListBM <TestItemBM> {
Metadata = { DataProvider = { Data = dl } }
};
bl.CollectionChanged += OnViewModelCollectionChangedCallInvalid;
bl.BeginUpdate();
Assert.Throws <InvalidOperationException>(() => bl.BeginUpdate());
bl.Add(TestItemBM.New());
bl.EndUpdate();
Assert.Throws <InvalidOperationException>(() => bl.EndUpdate());
bl.CollectionChanged -= OnViewModelCollectionChangedCallInvalid;
}