TDD - Business Rule Testing / Validation in ASP.NET MVC

Question

I use sharp architecture, so I can easily use mocks, etc. in their unit tests and / or during TDD. I have quite complex business rules and want to test them at the controller level. I just wonder how other people do it?

For me, validating business rules at three levels:

(1) Level of ownership (e.g. property required) (2) Level of ownership within the facility (e.g. start date and end date) (3) Persistence level (e.g. unique name, parent child cannot be a child)

My validation system also assigns properties to properties. I'm just wondering what other people are doing. Do you write a test for each business rule and verify that the correct error message is assigned correctly (i.e. Look at the ASP.MVC ModelState)?

Hope my question makes sense. Many thanks!

Regards,

Christian

Answer 1

I usually divide this into two:

• Check if the controller works correctly when the model is valid and when not.
• Test if the model, in combination with the rule engine, generates the correct error messages.

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  [TestClass]
    public class Maintaining_todo_list
    {
        private TodoController controller;

        [TestInitialize]
        public void Setup()
        {
            controller = new TodoController {ControllerContext = new ControllerContext()};
        }

        [TestMethod]
        public void Valid_update_should_redirect_to_list()
        {
            var result = controller.Edit(1, new TodoItem {Text = "todo"});
            result.ShouldRedirectTo("list");
        }

        [TestMethod]
        public void Invalid_update_should_display_same_view()
        {
            var result = controller.Edit(1, new TodoItem {Text = ""});
            result.ShouldDisplayDefaultView();
        }
    }

:

   [TestClass]
    public class Validating_todo_item
    {
        [TestMethod]
        public void Text_cannot_be_empty()
        {
            var todo = new TodoItem {Text = ""};
            todo.ShouldContainValidationMessage("Text cannot be empty");
        }

        [TestMethod]
        public void Text_cannot_contain_more_than_50_characters()
        {
            var todo = new TodoItem { Text = new string('a', 51) };
            todo.ShouldContainValidationMessage("Text cannot contain more than 50 characters");
        }

        [TestMethod]
        public void Valid_items()
        {
            new TodoItem { Text = new string('a', 1) }.ShouldBeValid();
            new TodoItem { Text = new string('a', 50) }.ShouldBeValid();
        }
    }

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 internal static class AssertionHelpers
    {
        public static void ShouldRedirectTo(this ActionResult result, string action)
        {
            var redirect = result as RedirectToRouteResult;

            Assert.IsNotNull(redirect);
            Assert.AreEqual(action, redirect.RouteValues["action"]);
            Assert.IsNull(redirect.RouteValues["controller"]);
        }

        public static void ShouldDisplayDefaultView(this ActionResult result)
        {
            var view = result as ViewResult;

            Assert.IsNotNull(view);
            Assert.AreEqual("", view.ViewName);
        }

        public static void ShouldContainValidationMessage(this TodoItem todo, string message)
        {
            var context = new ValidationContext(todo, null, null);
            var results = new List<ValidationResult>();

            Validator.TryValidateObject(todo, context, results, true);

            var errors = results.Select(result => result.ErrorMessage);

            foreach (var error in errors)
            {
                Console.Out.WriteLine(error);
            }

            Assert.IsTrue(errors.Contains(message));
        }

        public static void ShouldBeValid(this TodoItem todo)
        {
            var context = new ValidationContext(todo, null, null);
            var results = new List<ValidationResult>();
            var isValid = Validator.TryValidateObject(todo, context, results, true);
            Assert.IsTrue(isValid);
        }
    }