public void NameNotEmptyTest()
        {
            CityViewModel cityViewModel = new CityViewModel();

            cityViewModel.NameCity = "Moscow";
            bool notEmpty = cityViewModel.NameNotEmpty(cityViewModel.NameCity);

            cityViewModel.NameCity = null;
            bool nullString = !cityViewModel.NameNotEmpty(cityViewModel.NameCity);

            cityViewModel.NameCity = "";
            bool empty = !cityViewModel.NameNotEmpty(cityViewModel.NameCity);

            City.AllCities.Clear();

            Assert.IsTrue(notEmpty && nullString && empty);
        }