MVC Unit Testing with Unity Container

Question

I just have a quick question. Im trying to use Unity with my asp.net MVC project. Im coming across a problem when using the Unit of Work pattern with an EF context.

Say i inject the uow in the constructor, but have 4 or 5 actions in the controller that need to use the UnitOfWork in a using statement. This isnt going to work! Because Id have to do a
new UnitOfWork() in each action method.

should i be injecting a UnitOfWork into each action method? or into just the constructor? or should I even be injecting this at all!! The problem im facing is that i want to be able to unit test my controller with Mock data, and i can only do this if I inject the UnitOfWork or the DBContext.

k.m · Accepted Answer · 2013-01-14 16:43:00Z

3

Inject factory instead. This way you still achieve separation of concerns and loose coupling, yet you won't face any issues with using statements:

private IUnitOfWorkFactory factory;

public MyController(IUnitOfWorkFactory factory)
{
    this.factory = factory;
}

public ActionResult MyAction()
{
    using (var uow = factory.CreateUnitOfWork())
    {
        // ...
    }
}

Edit:

Natural advantage of such approach is its configurability - you can register whichever factory you like to serve different controllers and wire it up at composition root:

// Note: this isn't unity syntax, but I hope my point is clear
container.Register<ISessionFactory, ReusableSessionFactory>("Reusable");
container.Register<ISessionFactory, FreshSessionFactory>("Fresh");
container.Register<IController, LoginController>().With("Fresh");
container.Register<IController, HomeController>().With("Reusable");

Now,

LoginController will use factory that under the hood serves new session upon each request
HomeController on the other hand will reuse the same session for all its lifespan

It's worth noting that from the controller point of view, it's irrelevant which factory serves the session as it's a mere implementation detail. That's why we hide session factory dependency behind abstraction (interface in this example) and perform all the object-to-dependency binding at application's root.

edited Jan 14, 2013 at 16:43

answered Jan 14, 2013 at 12:58

k.m

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2 Comments

Neil Hosey Over a year ago

OK - that might work, but say i wanted to have say a session, instead of a unit of work, whereby wherever i call factory.CreateUnitOfWork(), it will return the same session, that will allow me to retrieve the same session? and thanks for the reply!!

k.m Over a year ago

@NeilHosey: it's up to you how you configure your factories - you can bind them to objects as you please. See my edit.

IsakBosman · Accepted Answer · 2013-01-14 12:42:36Z

If I understand correctly you simply want to be able to test the UOW with something like Moq?

In that case for good design principles and proper separation of concerns you should create a base context for your database that each repository class uses.

Then you should create a repository interface for each domain model entity. Then you can implement the interface in a seperate repository library (this way you can implement a POCO model)

Finally you either create a service layer between your domain objects and your action methods or just use the required repository interfaces within the action methods.

I answer it like this because it depends on your application infrastructure. If you have no service layer then the best practice is to do the following:

   public class AccountController : Controller
    {
        private readonly IAccountRepository _accountrepository;

        public AccountController(IAccountRepository repository)
        {
            _accountrepository = repository;
        }
}

I hope this helps.

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