public void Test_ConcurrentObservableCollection_RemoveRange_ByItems_IEnumerable()
{
var initial = Enumerable.Range(0, 100).Select(x => new KeyValuePair <int, int>(x, x));
var toRemove = Enumerable.Range(1, 40).Select(x => x * 2);
var collection = new ConcurrentObservableDictionary <int, int>();
collection.AddRange(initial);
Assert.AreEqual(100, collection.Count);
// Record all the collection changed events
List <(object, NotifyCollectionChangedEventArgs)> returnedList = new List <(object, NotifyCollectionChangedEventArgs)>();
collection.CollectionChanged += (s, e) => returnedList.Add((s, e));
collection.RemoveRange(toRemove);
// Check just one collection changed event was fired
Assert.AreEqual(1, returnedList.Count);
(var returnedObject, var returnedArgs) = returnedList[0];
Assert.IsNotNull(returnedObject);
Assert.IsNotNull(returnedArgs);
Assert.AreEqual(returnedObject, collection);
Assert.AreEqual(NotifyCollectionChangedAction.Remove, returnedArgs.Action);
Assert.AreEqual(-1, returnedArgs.OldStartingIndex);
Assert.IsNull(returnedArgs.NewItems);
Assert.IsNotNull(returnedArgs.OldItems);
Assert.AreEqual(toRemove.Count(), returnedArgs.OldItems.Count);
Assert.IsTrue(CollectionsAreEqual(toRemove, returnedArgs.OldItems));
}