How to moq a static class with a static method (UnitOfWork case)?

Question

I have these classes:

public static class UnitOfWorkSS 
{
  public static IUnitOfWork Begin()
  {
    return IoC.Resolve<IUnitOfWork>();
  }
}

public class PostService
{
  using (IUnitOfWork unitOfWork = UnitOfWorkSS.Begin())
  {
    //don't forget to sanitize html content
    htmlContent = _htmlSanitizer.Sanitize(htmlContent);

    IPost post = _factory.CreatePost(byUser, title, htmlContent);                    

    _postRepository.Add(post);

    unitOfWork.Commit();
  }
}

How can I mock the classes UnitOfWorkSS and unitOfWork?

Answer 1

It looks like the only thing you are doing with the call to Begin() is returning your configured class for that particular interface: IUnitOfWork

You really just need to make sure that your call to Begin() returns a mock implementation of IUnitOfWork

One of two ways you can do this:

Option One - Refactor UnitOfWorkSS so that you can set the instance of IUnitOfWork to be returned

public static class UnitOfWorkSS  
{
    private static IUnitOfWork _unitOfWork;
    public static IUnitOfWork UnitOfWork
    {
        set { _unitOfWork = value; }
        private get{ _unitOfWork ?? (_unitOfWork = IoC.Resolve<IUnitOfWork>()); }
    }

    public static IUnitOfWork Begin()  
    {  
        return UnitOfWork;
    }  
}  

[TestMethod]
public void DoStuff()
{
    var mockUnitOfWork = new Mock<IUnitOfWork>();
    UnitOfWorkSS.UnitOfWork = mockUnitOfWork.Object;

    //Do some setup and verify
}

Option Two - Simply register a mock instance of IUnitOfWork with your IoC Container

private Mock<IUnitOfWork> _mockUnitOfWork;

[TestInitialize]
public void Init()
{
    _mockUnitOfWork = new Mock<IUnitOfWork>();

    //Making a lot of assumptions about your IoC here...
    IoC.Register<IUnitOfWork>(_mockUnitOfWork.Object);
}

[TestMethod]
public void DoStuff()
{
    _mockUnitOfWork.Setup( ... );

    //Do some verification
}

Answer 2

Mock the IUnitOfWork and register it into your container so that it can be resolved.