public void RemoveWhereTest() { var collection = new MyObservableCollection <int>(); collection.AddRange(Enumerable.Range(0, 31)); collection.RemoveWhere(val => { int remainder; int div = Math.DivRem(val, 3, out remainder); return(remainder == 0); }); collection.ForEach(val => { int remainder; int div = Math.DivRem(val, 3, out remainder); Assert.IsFalse(remainder == 0); }); }