public void AddPhoneToUserShouldChangeOrAddPhoneToUser()
        {
            DbContextOptions <UltimateMoviesDbContext> options = new DbContextOptionsBuilder <UltimateMoviesDbContext>()
                                                                 .UseInMemoryDatabase(databaseName: "Users_AddPhoneToUser_Database")
                                                                 .Options;
            UltimateMoviesDbContext db = new UltimateMoviesDbContext(options);

            IUsersService usersService = new UsersService(db);

            db.Users.Add(new UMUser {
                UserName = "******"
            });

            db.SaveChanges();

            usersService.AddPhoneToUser("Tester", "080011100");

            Assert.Equal("080011100", db.Users.Last().PhoneNumber);
        }