Why doesn't validation work when testing a controller?

Question

ASP.NET

there is a controller for creating a new user, a model should come into it. I send an empty model through the test and no error comes out. if you add it manually, then everything is triggered by the
controller:

public async Task<ActionResult> Create([FromBody]RegisterViewModel user)
        {
           // ModelState.AddModelError("swe","ssssss");
  
            if (ModelState.IsValid)
            {
                var result = await _userService.Create(user);
                return Ok(user);
            }

            else
            {
                return BadRequest(ModelState);
            }
        }

model:

public class RegisterViewModel
    {
        //обязательные поля
        [Required(ErrorMessage = "Пустое поле")]
        public string FirstName { get; set; }


        [Required(ErrorMessage = "Пустое поле")]
        public string FullName { get; set; }


        [Required(ErrorMessage = "Пустое поле")]
        public string UserName { get; set; }

}

test:

public void CheckAddUser()
        {
            RegisterViewModel fakeUser = new RegisterViewModel();
            
            fakeUser.Password = null;
            fakeUser.UserName = null;
            fakeUser.Email = null;
            
            
            var moc = new Mock<IUserService>();
            moc.Setup(c => c.Create(It.IsAny<RegisterViewModel>()) );
            

            var userController = new TestController(moc.Object);

            var result = userController.Create(fakeUser);
//должен вернуть ошибку
          //  Assert.IsInstanceOf(result.GetType(),typeof(BadRequestResult));
            Assert.AreSame(result,typeof(BadRequestResult));
          

        }

Answer 1

Most likely, asp does the validation, not the controller, and when creating the controller, it passes the ModelState to it.