I am new to unit testing and i'd like to know why it is not working - asp.net-mvc

Question

I am new to MVC and to unit testing so I have been following guides etc.
At the moment I am looking at unit testing. I have a test which as far as I can see should work, but unfortunately does not.
using Microsoft.AspNetCore.Mvc;
using System.Collections.Generic;
using WorkingWithVisualStudio.Controllers.Home;
using WorkingWithVisualStudio.Models;
using Xunit;
namespace WorkingWithVisualStudio.Tests
{
public class HomeControllerTests
{
class ModelCompleteFakeRepository : IRepository
{
public IEnumerable<Product> Products { get; } = new Product[] {
new Product { Name = "P1", Price = 275M },
new Product { Name = "P2", Price = 48.95M },
new Product { Name = "P3", Price = 19.50M },
new Product { Name = "P3", Price = 34.95M }};
public void AddProduct(Product p)
{
// do nothing - not required for test
}
}
[Fact]
public void IndexActionModelIsComplete()
{
// Arrange
var controller = new HomeController();
controller.Repository = new ModelCompleteFakeRepository();
// Act
var model = (controller.Index() as ViewResult)?.ViewData.Model
as IEnumerable<Product>;
// Assert
Assert.Equal(controller.Repository.Products, model,
Comparer.Get<Product>((p1, p2) => p1.Name == p2.Name
&& p1.Price == p2.Price));
}
class ModelCompleteFakeRepositoryPricesUnder50 : IRepository
{
public IEnumerable<Product> Products { get; } = new Product[] {
new Product { Name = "P1", Price = 5M },
new Product { Name = "P2", Price = 48.95M },
new Product { Name = "P3", Price = 19.50M },
new Product { Name = "P3", Price = 34.95M }};
public void AddProduct(Product p)
{
// do nothing - not required for test
}
}
[Fact]
public void IndexActionModelIsCompletePricesUnder50()
{
// Arrange
var controller = new HomeController();
controller.Repository = new ModelCompleteFakeRepositoryPricesUnder50();
// Act
var model = (controller.Index() as ViewResult)?.ViewData.Model
as IEnumerable<Product>;
// Assert
Assert.Equal(controller.Repository.Products, model,
Comparer.Get<Product>((p1, p2) => p1.Name == p2.Name
&& p1.Price == p2.Price));
}
}
}
When I run the IndexActionModelIsCompletePricesUnder50()
I get the following:
Message: Assert.Equal() Failure
Expected: Product[] [Product { Name = "P1", Price = 5 }, Product { Name = "P2", Price = 48.95 }, Product { Name = "P3", Price = 19.50 }, Product { Name = "P3", Price = 34.95 }]
Actual: ValueCollection<String, Product> [Product { Name = "Kayak", Price = 275 }, Product { Name = "Lifejacket", Price = 48.95 }, Product { Name = "Soccer ball", Price = 19.50 }, Product { Name = "Corner flag", Price = 34.95 }]
My model is as follows:
public class Product
{
public string Name { get; set; }
public decimal Price { get; set; }
}
My repository:
public class SimpleRepository : IRepository
{
private static SimpleRepository sharedRepository = new SimpleRepository();
private Dictionary<string, Product> products = new Dictionary<string, Product>();
public static SimpleRepository SharedRepository => sharedRepository;
public SimpleRepository()
{
var initialItems = new[]
{
new Product {Name = "Kayak", Price = 275M},
new Product { Name = "Lifejacket", Price = 48.95M },
new Product { Name = "Soccer ball", Price = 19.50M },
new Product { Name = "Corner flag", Price = 34.95M }
};
foreach(var p in initialItems)
{
AddProduct(p);
}
//products.Add("Error", null);
}
public IEnumerable<Product> Products => products.Values;
public void AddProduct(Product p) => products.Add(p.Name, p);
}
My repository interface
public interface IRepository
{
IEnumerable<Product> Products { get; }
void AddProduct(Product p);
}
My comparer:
public class Comparer
{
public static Comparer<U> Get<U>(Func<U, U, bool> func)
{
return new Comparer<U>(func);
}
}
public class Comparer<T> : Comparer, IEqualityComparer<T>
{
private Func<T, T, bool> comparisonFunction;
public Comparer(Func<T, T, bool> func)
{
comparisonFunction = func;
}
public bool Equals(T x, T y)
{
return comparisonFunction(x, y);
}
public int GetHashCode(T obj)
{
return obj.GetHashCode();
}
}
my controller:
public class HomeController : Controller
{
public IRepository Repository = SimpleRepository.SharedRepository;
public IActionResult Index() => View(SimpleRepository.SharedRepository.Products);
[HttpGet]
public IActionResult AddProduct() => View(new Product());
[HttpPost]
public IActionResult AddProduct(Product p)
{
Repository.AddProduct(p);
return RedirectToAction("Index");
}
}
I am sorry if this seems like a stupid question but I have only just begun to look into unit testing. If someone could explain to me what the issue is I would definitely appreciate it. Thank you very much to those who take the time to lend a hand.

Answer 1

I would first suggest you refactor the controller to follow a more SOLID approach by using Explicit Dependency Principle
Methods and classes should explicitly require (typically through method parameters or constructor parameters) any collaborating objects they need in order to function correctly.
So the controller would end up looking like this
public class HomeController : Controller {
private readonly IRepository repository;
public HomeController(IRepository repository) {
this.repository = repository;
}
public IActionResult Index() => View(repository.Products.ToList());
[HttpGet]
public IActionResult AddProduct() => View(new Product());
[HttpPost]
public IActionResult AddProduct(Product p) {
repository.AddProduct(p);
return RedirectToAction("Index");
}
}
So as to avoid the mistake initially made with accessing the share repository during an isolated unit test, which caused your assertions to fail.
Try to avoid tightly coupling your classes to static or shared dependencies. It would be safer to inject the abstraction of that dependency.
A simplified version of the test can now be clearly exercised as follows.
class ModelCompleteFakeRepository : IRepository {
public IEnumerable<Product> Products { get; } = new Product[] {
new Product { Name = "P1", Price = 275M },
new Product { Name = "P2", Price = 48.95M },
new Product { Name = "P3", Price = 19.50M },
new Product { Name = "P3", Price = 34.95M }
};
public void AddProduct(Product p) {
// do nothing - not required for test
}
}
[Fact]
public void IndexActionModelIsComplete() {
// Arrange
var repository = new ModelCompleteFakeRepository();
var controller = new HomeController(repository);
var expected = repository.Products;
// Act
var actual = (controller.Index() as ViewResult)?.ViewData.Model as IEnumerable<Product>;
// Assert
Assert.IsNotNull(actual);
Assert.Equal(expected, actual);
}

Answer 2

Because in your Index method you're referring to the SimpleRepository, not you Repository member.
Replace
public IActionResult Index() => View(SimpleRepository.SharedRepository.Products);
with
public IActionResult Index() => View(Repository.Products);
I should add as well that you might want to have a look at the structure of your code, and inject the repository in the constructor instead. And also, the two different tests you have test the same thing, so only one of them is necessary.
Edit: My answers solves your current issue, while #Nkosi answer shows how you should do this properly.