public MainWindowViewModel(ITestDataService testDataService)
        {
            Argument.IsNotNull(() => testDataService);

            _testDataService = testDataService;

            RawItems = _testDataService.GenerateTestItems();
            FilteredItems = new FastObservableCollection<TestEntity>();

            FilteredItems.CollectionChanged += (sender, e) => Console.WriteLine("Collection updated");
        }