public void InitializeTestData()
        {
            _recievedEvents = new List <string>();

            _persons = new ObservableCollectionWithUniquePropertyValue <Person, string>("LastName")
            {
                new Person {
                    FirstName = "John", LastName = "Doe"
                },
                new Person {
                    FirstName = "John", LastName = "Smith"
                }
            };

            _persons.ItemPropertyChanged += (sender, args) => { _recievedEvents.Add(args.PropertyName); };
        }
 public void CleanupTestData()
 {
     _persons        = null;
     _recievedEvents = null;
 }