public void Objects_references_are_preserved()
{
var tweet = new Tweet {
Username = "******"
};
_list.Add(tweet);
_list.Add(tweet);
_list.Save();
_list = new PersistentList <Tweet>(_store, null, null);
var t1 = _list.First();
var t2 = _list.Last();
Assert.Same(t1, t2);
}