[Asp.net-mvc] ASP/NET MVC: Test Controllers w/Sessions? Mocking?


Answers

The ASP.NET MVC framework is not very mock-friendly (or rather, requires too much setup to mock properly, and causes too much friction when testing, IMHO) due to it's use of abstract base classes instead of interfaces. We've had good luck writing abstractions for per-request and session-based storage. We keep those abstractions very light and then our controllers depend upon those abstractions for per-request or per-session storage.

For example, here's how we manage the forms auth stuff. We have an ISecurityContext:

public interface ISecurityContext
{
    bool IsAuthenticated { get; }
    IIdentity CurrentIdentity { get; }
    IPrincipal CurrentUser { get; set; }
}

With a concrete implementation like:

public class SecurityContext : ISecurityContext
{
    private readonly HttpContext _context;

    public SecurityContext()
    {
        _context = HttpContext.Current;
    }

    public bool IsAuthenticated
    {
        get { return _context.Request.IsAuthenticated; }
    }

    public IIdentity CurrentIdentity
    {
        get { return _context.User.Identity; }
    }

    public IPrincipal CurrentUser
    {
        get { return _context.User; }
        set { _context.User = value; }
    }
}
Question

I read some of the answers on here re: testing views and controllers, and mocking, but I still can't figure out how to test an ASP.NET MVC controller that reads and sets Session values (or any other context based variables.) How do I provide a (Session) context for my test methods? Is mocking the answer? Anybody have examples? Basically, I'd like to fake a session before I call the controller method and have the controller use that session. Any ideas?




How to unit test library that relies on Session object

You can use mock helpers such as seen here




Friction in Settingup test using abstract classes rather than Interfaces

I can only think of one relevant difference with respect to unit testing (if we're ruling out default implementations): an abstract classes' methods may be sealed,* in which case they cannot be mocked, while interfaces never have this problem.

* Or final, or not declared virtual in the first place depending on the language.