Unit testing ModelState using Moq

CarController.cs

using System.Web.Mvc;

namespace MyApp
{
    public class CarController : Controller
    {
        //...

        public ActionResult Edit(CarModel model)
        {
            if (ModelState.IsValid) {
              //Save the model
              return View("Details", model);
            }

            return View(model);
        }

        //...
    }
}

CarModel.cs

using System;
using System.ComponentModel.DataAnnotations;

namespace MyNamespace.Model
{
    public class CarModel
    {
        [Required,
         Display(Name = "Purchased"),
         DisplayFormat(DataFormatString = "{0:d}", ApplyFormatInEditMode = true)]
        public DateTime Purchased { get; set; }

        [Required,
         Display(Name = "Colour")]
        public string Colour{ get; set; }
    }
}

ModelStateTestController.cs

using System.Web.Mvc;
using Moq;

namespace UnitTests.TestUtilities
{
    /// <summary>
    /// Instance of a controller for testing things that use controller methods i.e. controller.TryValidateModel(model)
    /// </summary>
    public class ModelStateTestController : Controller
    {
        public ModelStateTestController()
        {
            ControllerContext = (new Mock<ControllerContext>()).Object;
        }

        public bool TestTryValidateModel(object model)
        {
            return TryValidateModel(model);
        }
    }
}

ModelStateUnitTests.cs

        [TestMethod]
        public void Unit_Test_CarModel_ModelState_validations_are_thrown()
        {
            // Arrange
            var controller = new ModelStateTestController();
            var car = new CarModel
            {
              Puchased = null, //This is a required property and so this value is invalid
              Colour = null //This is a required property and so this value is invalid
            };

            // Act
            var result = controller.TestTryValidateModel(company);

            // Assert
            Assert.IsFalse(result);

            var modelState = controller.ModelState;

            Assert.AreEqual(2, modelState.Keys.Count);

            Assert.IsTrue(modelState.Keys.Contains("Purchased"));
            Assert.IsTrue(modelState["Purchased"].Errors.Count == 1);
            Assert.AreEqual("The Purchased field is required.", modelState["Purchased"].Errors[0].ErrorMessage);
            
            Assert.IsTrue(modelState.Keys.Contains("Colour"));
            Assert.IsTrue(modelState["Colour"].Errors.Count == 1);
            Assert.AreEqual("The Colour field is required.", modelState["Colour"].Errors[0].ErrorMessage);
        }

NaomiCampbell.cs

            var car = new CarModel
            {
              Puchased = null, //This is a required property and so this value is invalid
              Colour = null //This is a required property and so this value is invalid
            };