How to do unit testing using Moq in Asp.Net MVC Entity Framework.md

How to do unit testing using Moq in Asp.Net MVC Entity Framework?

Problem

How to do unit testing in .Net without relying on dependencies such as databases, external services, or components?

Environment

Visual Studio, Asp.Net MVC, C#

How you fix it

By following the steps given in the solution below:

Solution

You can do the unit testing of an application without relying on dependencies such as databases, external services, or components by following these steps

• Right click on sloution >> Add >> Test >> Unit Test Project >> give it name and click create.
• After creating the project, you must install the Moq library from the NuGet packages manager.
• Then add a reference of your application in the Unit test project. Suppose we have the following controller in our application and want to do its unit testing.

namespace FirstCrust2._0.Controllers
{
    public class CategoriesController : Controller
    {
        public ApplicationDbContext db = new ApplicationDbContext();
        // GET: Categories
        public ActionResult Index()
        {
            return View(db.Category.ToList());
        }

        // GET: Categories/Details/5
        public ActionResult Details(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            Category category = db.Category.Find(id);
            if (category == null)
            {
                return HttpNotFound();
            }
            return View(category);
        }
    }
}

In order to do unit testing of the above controller we need to write seprate tests for each of Action methods in the class of unit test project. As shown below

namespace FirstCRUSTTest
{
    [TestClass]
    public class CategoryTest
    {

        // Arrang
        private List<Category> GetFakeEmployeeList()
        {
            return new List<Category>
            {
                new Category { CreatedBy = "Adnan", ID = 1, IsActive=true, ModifiedBy="Irfan", Name="Cake" },
                new Category { CreatedBy = "Ali", ID = 2, IsActive = true, ModifiedBy = "Ashraf", Name = "Biscuts" },
                    // Add more categories as needed
            };    
        }
        [TestMethod]
        public void Index()
        {
            // Arrange
            var categories = new List<Category>
            {
                new Category { CreatedBy = "Adnan", ID = 1, IsActive=true, ModifiedBy="Habib", Name="Cake" },
                new Category { CreatedBy = "Ali", ID = 2, IsActive = true, ModifiedBy = "Zara", Name = "Biscuts" }
            };
            var mockSet = new Mock<DbSet<Category>>();
            mockSet.As<IQueryable<Category>>().Setup(m => m.Provider).Returns(categories.AsQueryable().Provider);
            mockSet.As<IQueryable<Category>>().Setup(m => m.Expression).Returns(categories.AsQueryable().Expression);
            mockSet.As<IQueryable<Category>>().Setup(m => m.ElementType).Returns(categories.AsQueryable().ElementType);
            mockSet.As<IQueryable<Category>>().Setup(m => m.GetEnumerator()).Returns(categories.AsQueryable().GetEnumerator());

            var mockContext = new Mock<ApplicationDbContext>();
            mockContext.Setup(db => db.Category).Returns(mockSet.Object);

            var controller = new CategoriesController();
            controller.db = mockContext.Object;

            // Act
            var result = controller.Index() as ViewResult;

            // Assert
            Assert.IsNotNull(result);
            Assert.AreEqual(categories.Count, (result.Model as List<Category>).Count);
        }
        [TestMethod]
        public void Details()
        {
            // Arrange
            
            int categoryId = 1;
            var category = new Category { ID = 1, Name = "Cake" };
            var mockSet = new Mock<DbSet<Category>>();
            mockSet.Setup(m => m.Find(categoryId)).Returns(category);
            var mockContext = new Mock<ApplicationDbContext>();
            mockContext.Setup(db => db.Category).Returns(mockSet.Object);
            var controller = new CategoriesController();
            controller.db = mockContext.Object;

            // Act
            var result = controller.Details(categoryId) as ViewResult;

            // Assert
            Assert.IsNotNull(result);
            Assert.AreEqual(category, result.Model);
        }

        [TestMethod]
        public void Details_NullId_ReturnsBadRequest()
        {
            // Arrange
            int? categoryId = null;
            var controller = new CategoriesController();

            // Act
            var result = controller.Details(categoryId) as HttpStatusCodeResult;

            // Assert
            Assert.IsNotNull(result);
            Assert.AreEqual(HttpStatusCode.BadRequest, (HttpStatusCode)result.StatusCode);
        }

        [TestMethod]
        public void Details_InvalidId_ReturnsHttpNotFound()
        {
            // Arrange
            int categoryId = 999;
            var mockSet = new Mock<DbSet<Category>>();
            mockSet.Setup(m => m.Find(categoryId)).Returns((Category)null);
            var mockContext = new Mock<ApplicationDbContext>();
            mockContext.Setup(db => db.Category).Returns(mockSet.Object);
            var controller = new CategoriesController();
            controller.db = mockContext.Object;

            // Act
            var result = controller.Details(categoryId) as HttpNotFoundResult;

            // Assert
            Assert.IsNotNull(result);
        }
        [TestMethod]
        public void Create()
        {
            // Arrange
            var controller = new CategoriesController();

            // Act
            var result = controller.Create() as ViewResult;

            // Assert
            Assert.IsNotNull(result);
        }
    }
}

• Now you can simply Run the All the tests by selecting Test button from the title bar.