public void Model_ModelUpdated()
{
_model = new Model(3);
_model.ModelUpdated += new EventHandler(_model_ModelUpdated);
List<Mail> mailList = new List<Mail>();
mailList.Add(new Mail() { From = "U1", Date = new DateTime(2000, 1, 1, 0, 1, 1) });
mailList.Add(new Mail() { From = "U1", Date = new DateTime(2000, 1, 1, 3, 1, 1) });
foreach (Mail m in mailList)
_model.AddMail(m);
Assert.IsFalse(_modelUpdated);
Mail last = new Mail() { From = "U3", Date = new DateTime(2000, 1, 1, 7, 1, 1) };
_model.AddMail(last);
Assert.IsTrue(_modelUpdated);
}