public void SetCurrentElementTest()
        {
            User user = new User("Ivan", "Ivanov", "Ivanovich");
            UserDataController userDataController = new UserDataController(user);

            Assert.IsTrue(userDataController.SetCurrentElement(user.Surname));
            Assert.AreEqual(user, userDataController.GetCurrentElement());
        }
        public void AddElementTest()
        {
            User user = new User("Ivan", "Ivanov", "Ivanovich");
            UserDataController userDataController = new UserDataController(user);

            User user1 = new User("S***n", "Semenov", "Semenovich");

            userDataController.AddElement(user1);
            userDataController.SetCurrentElement("Semenov");
            Assert.AreEqual(user1, userDataController.GetCurrentElement());
        }