public void Insert_OneItemAtSecondIndex_ItemIsAddedAndCollectionChangedRaised() { var collectionChangedEventArgsList = new List <NotifyCollectionChangedEventArgs>(); var collection = new ExtendedObservableCollection <int> { 123, 456, 789 }; collection.CollectionChanged += (_, args) => collectionChangedEventArgsList.Add(args); collection.Insert(1, 0); Assert.Equal(4, collection.Count); Assert.Equal(new[] { 123, 0, 456, 789 }, collection); Assert.Single(collectionChangedEventArgsList); Assert.Equal(NotifyCollectionChangedAction.Add, collectionChangedEventArgsList[0].Action); Assert.NotNull(collectionChangedEventArgsList[0].NewItems); Assert.Single(collectionChangedEventArgsList[0].NewItems); Assert.Equal(0, collectionChangedEventArgsList[0].NewItems[0]); }