Mocking UnitOfWork with Moq and EF 4.1

Question

I am working my way through the Contoso sample for some TDD practice and my tests for retrieving students are passing.

My test for creating a new student fails (although the actual code works) as I believe the DBContext is not being mocked.

What should I refactor in order to get this test to past?

The test fails as so:

Contoso.Tests.Controllers.StudentControllerTest.Create_HttpPost_Should_Save_New_Student: Expected: 9 But was: 8

Heres the concrete UnitOfWork

public class UnitOfWork : IUnitOfWork
{
    private SchoolContext context = new SchoolContext();

    private IStudentsRepository studentsRepository;

    private bool disposed = false;

    public IStudentsRepository StudentsRepository
    {
        get
        {
            if (this.studentsRepository == null)
            {
                this.studentsRepository = new StudentsRepository(context);
            }
            return studentsRepository;
        }
    }


    public void Save()
    {
        context.SaveChanges();
    }


    protected virtual void Dispose(bool disposing)
    {
        if (!this.disposed)
        {
            if (disposing)
            {
                context.Dispose();
            }
        }
        this.disposed = true;
    }

    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }
}

The StudentController

public class StudentController : Controller
{
    private IUnitOfWork _unitOfWork;

    public StudentController(IUnitOfWork unitOfWork)
    {
        this._unitOfWork = unitOfWork;
    }

...

    [HttpPost]
    public ActionResult Create(Student student)
    {
        if (ModelState.IsValid)
        {
            _unitOfWork.StudentsRepository.Add(student);
            _unitOfWork.StudentsRepository.Save();

            return RedirectToAction("Details", new { id = student.StudentID });
        }

        return View(student);
    }

...
}

Here's where I mock the IUnitOfWork

    public static IUnitOfWork MockUnitOfWork(List<Student> students)
    {
        var mockUnitOfWork = new Mock<IUnitOfWork>();

        mockUnitOfWork.Setup(x => x.StudentsRepository.Students()).Returns(students.AsQueryable());

        return mockUnitOfWork.Object;
    }

Here's the failing test

private IUnitOfWork unitOfWork = UnitTestHelpers.MockUnitOfWork(testData);
...



    [Test]
    public void Create_HttpPost_Should_Save_New_Student()
    {
        // Arrange
        var studentsCount = unitOfWork.StudentsRepository.Students().Count();
        var controller = new StudentController(unitOfWork);
        var student = Fakes.FakeStudentsData.CreateStudent();

        // Act
        var result = controller.Create(student);

        // Assert
        Assert.AreEqual(studentsCount+1, unitOfWork.StudentsRepository.Students().Count());
        Assert.IsInstanceOf(typeof(RedirectToRouteResult), result);
    }

Could you provide StudentController sources? What exception is thrown? — Restuta, Jul 24 '11 at 21:49
Sorry to resurrect this question, but where is this sample code? I am writing my own app, whose controllers also implement UnitOfWork, and I am wondering if I should inject the unitofwork into my controllers and how that all works (for the sake of unit testing my controllers down the road). Thanks! — Killnine, Jun 26 '12 at 18:49
http://www.asp.net/mvc/tutorials/getting-started-with-ef-using-mvc and http://nicholascontoso.codeplex.com/ — Nicholas Murray, Jun 26 '12 at 21:44

score 5 · Accepted Answer · answered Jul 25 '11 at 01:14

5

It looks like the Add method for StudentRepository needs to be mocked as well. I'm not if sure if the syntax is right, but try the following:

public static IUnitOfWork MockUnitOfWork(List<Student> students)
{
    var mockUnitOfWork = new Mock<IUnitOfWork>();

    mockUnitOfWork.Setup(x => x.StudentsRepository.Students()).Returns(students.AsQueryable());
    mockUnitOfWork.Setup(x => x.StudentsRepository.Add(It.IsAny<Student>())).Callback<Student>((s) => students.Add(s));

    return mockUnitOfWork.Object;
}

answered Jul 25 '11 at 01:14

John Allers

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thanks! that passes the test. Is there a way to increment the ID when adding a new student? – Nicholas Murray Jul 25 '11 at 23:02
You mightbe able to expand on the Callback with something like: ...Callback((s) => { students.Add(s); s.ID = students.Select(x => x.ID).Max() + 1; }); – John Allers Jul 26 '11 at 12:55
Cool. I'll try that tonight, was thinking about redirecting to details page after adding a new student, so I'd have to pass an ID. Is there a good tutorial on the web to learn mocking? – Nicholas Murray Jul 26 '11 at 13:05
1

The Moq QuickStart is pretty good (http://code.google.com/p/moq/wiki/QuickStart) and there are other links from there. – John Allers Jul 26 '11 at 13:22
Oh course! Been there before but now its a lot more relevant. – Nicholas Murray Jul 26 '11 at 13:50

Mocking UnitOfWork with Moq and EF 4.1

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