public async Task AssignUserToSchoolShouldAddTheUserToTheSchool()
        {
            var dbOptions = new DbContextOptionsBuilder <ApplicationDbContext>()
                            .UseInMemoryDatabase("test");
            var context       = new ApplicationDbContext(dbOptions.Options);
            var schoolService = new SchoolService(context, null);

            var school = new School();
            var user   = new ApplicationUser();
            await context.Schools.AddAsync(school);

            await context.Users.AddAsync(user);

            await context.SaveChangesAsync();

            await schoolService.AssignUserToSchool(user, school.Id);

            var updatedUser = context.Users
                              .FirstOrDefault(x => x.Id == user.Id);

            Assert.False(string.IsNullOrWhiteSpace(updatedUser.SchoolId));
        }