How can I test ModelState?

How can I test Controller.ViewData.ModelState? I would prefer to do it without any mock framework.

From stackoverflow

• You don't have to use a Mock if you're using the Repository Pattern for your data, of course.

  Some examples: http://www.singingeels.com/Articles/Test_Driven_Development_with_ASPNET_MVC.aspx

  // Test for required "FirstName".
     controller.ViewData.ModelState.Clear();
  
     newCustomer = new Customer
     {
         FirstName = "",
         LastName = "Smith",
         Zip = "34275",    
     };
  
     controller.Create(newCustomer);
  
     // Make sure that our validation found the error!
     Assert.IsTrue(controller.ViewData.ModelState.Count == 1, "FirstName must be required.");