public void RandomlyChangeIndex()
        {
            RandomGenerator.ResetRandomGenerator();

            var list = new ObservableList <int>();

            foreach (var value in Enumerable.Range(0, 100))
            {
                list.Add(list.Count, RandomGenerator.GenerateRandomInteger());
            }

            var index = new ActiveValue <int>();

            var sut       = list.ActiveSkip(index);
            var watcher   = new CollectionSynchronizationWatcher <int>(sut);
            var validator = new LinqValidator <int, int, int>(list, sut, l => l.Skip(index.Value), false, null);

            foreach (var value in Enumerable.Range(0, 100))
            {
                index.Value = RandomGenerator.GenerateRandomInteger(-10, 110);

                validator.Validate();
            }
        }