How do you use Moq to mock a simple interface?

Question

Okay, I have a business logic class like this:

Note: For context, Vendor Briefs are simple entities that describe a "download" for a PDF document.

/// <summary>
/// Houses business level functions for dealing with vendor briefs.
/// </summary>
public class VendorBriefController : IVendorBriefController
{
    /// <summary>
    /// Vendor brief controller requires an instance of IVendorBriefRepository.
    /// </summary>
    IVendorBriefRepository _vendorBriefRepository;

    /// <summary>
    /// Initializes an instance of VendorBriefController.
    /// </summary>
    public VendorBriefController(IVendorBriefRepository vendorBriefRepository)
    {
        _vendorBriefRepository = vendorBriefRepository;
    }

    /// <summary>
    /// Get a list of string filters for vendor briefs.
    /// </summary>
    /// <returns>A list of string filters.</returns>
    public dynamic GetFilters()
    {
        List<string> filters = new List<string>
        {
            "All",
            "Active",
            "Inactive"
        };
        return filters;
    }

    /// <summary>
    /// Retrieve vendor brief entity from the repository by its unique ID.
    /// </summary>
    /// <param name="Id">The unique ID of the vendor brief.</param>
    /// <returns>A vendor brief entity.</returns>
    public VendorBrief GetVendorBriefForEditing(int Id)
    {
        var vendorBrief = _vendorBriefRepository.GetVendorBrief(Id);
        return vendorBrief;
    }

    /// <summary>
    /// Get a dynamic list of vendor briefs from the repository based on the supplied filter.
    /// </summary>
    /// <param name="filter">The filter to be used when retrieving vendor briefs.</param>
    /// <returns>A dynamic sorted & filtered list of vendor briefs to be displayed in a grid view.</returns>
    public dynamic GetVendorBriefList(string filter)
    {
        IEnumerable<VendorBrief> results = _vendorBriefRepository.GetVendorBriefs();
        switch (filter)
        {
            default:
                results = _vendorBriefRepository.GetVendorBriefs();
                break;
            case "Active":
                results = _vendorBriefRepository.GetVendorBriefs(true);
                break;
            case "Inactive":
                results = _vendorBriefRepository.GetVendorBriefs(false);
                break;
        }
        return from x in results
               orderby x.DisplayOrder
               select new
               {
                   ID = x.VendorBriefID,
                   Title = x.Title,
                   Active = x.IsActive,
                   DisplayOrder = x.DisplayOrder
               };
    }

    /// <summary>
    /// Save changes to the underlying repository in order to persist changes made to self-tracking vendor brief entities.
    /// </summary>
    /// <param name="vendorBrief"></param>
    public void EditVendorBrief(VendorBrief vendorBrief)
    {
        _vendorBriefRepository.SaveChanges();
    }

    /// <summary>
    /// Remove a vendor brief from the underlying repository.
    /// </summary>
    /// <param name="vendorBrief">The vendor brief to be removed.</param>
    public void DeleteVendorBrief(VendorBrief vendorBrief)
    {
        _vendorBriefRepository.DeleteVendorBrief(vendorBrief);
        _vendorBriefRepository.SaveChanges();
    }

    /// <summary>
    /// Add a vendor brief to the underlying repository.
    /// </summary>
    /// <param name="vendorBrief">The vendor brief to be added.</param>
    public void AddVendorBrief(VendorBrief vendorBrief)
    {
        _vendorBriefRepository.AddVendorBrief(vendorBrief);
        _vendorBriefRepository.SaveChanges();
    }
}

I am taking my first steps into unit testing and I'm learning about Moq. I don't want a whole unit test class written for this (unless you feel like it of course :P) but a simple sample will do. I'm assuming I need to "mock" IVendorBriefRepository so that I can pass it into the constructor when building my controller (not to be confused with mvc controllers), but I'm not sure how to do it. A sample using some of my own code will really help me get started.

Thanks in advance!

Solution 1

Something like this would test DeleteVendorBrief, for example.

Mock<IVendorBriefRepository> mock = new Mock<IVendorBriefRepository>();

VendorBriefController controller = new VendorBriefController(mock.Object);

VendorBrief brief = new VendorBrief();

controller.DeleteVendorBrief(brief);

mock.Verify(f=>f.DeleteVendorBrief(brief));
mock.Verify(f=>f.SaveChanges());

Solution 2

If you don't need to setup any special behavior for your Mocked object and just want a faked object to pass into a simple unit test, you can also use the shorter Mock.Of<T>() syntax.

The benefit here is that you don't need to remember to pass in the .Object.

Taking Brook's code as a reference:

Mock<IVendorBriefRepository> mock = Mock.Of<IVendorBriefRepository>();

VendorBriefController controller = new VendorBriefController(mock);
//...

Especially if your code uses Dependency Injection and pass in a lot of dependencies, this syntax makes the code cleaner to read.

Comments

[MrFranzén]

A small thing but, Mock.Of<IVendorBriefRepository>(); returns an (mocked) object of type IVendorBriefRepository. So the first line should be IVendorBriefRepository mock = Mock.Of<IVendorBriefRepository>(); .