Simplest way to mock properties of PostSharp attribute

Question

I'm using a PostSharp method attribute to do authorisation and auditing on my WCF service. It's working properly but now I'm trying to get my unit tests working with the attribute and am struggling to find a way to mock and inject the properties on the attribute.

My attribute is as below.

[Serializable]
[AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
public class AuthoriseAndAuditAttribute : OnMethodBoundaryAspect
{
    private static ILog logger = AppState.logger;

    private static Ninject.IKernel _kernel = MyKernel.Kernel;

    private UserRoleTypesEnum _requiredRole = UserRoleTypesEnum.None;

    [Inject]
    public IServiceAuthToken _serviceAuthToken { get; set; }

    [Inject]
    public UserSessionDataLayer _userSessionDataLayer { get; set; }

    public AuthoriseAndAuditAttribute(UserRoleTypesEnum role = UserRoleTypesEnum.None)
    {
        _requiredRole = role;
        _kernel.Inject(this);
    }

    public override void OnEntry(MethodExecutionArgs args)
    {
        // Get the user's session from cookie.
        UserSession userSession = GetUserSession();

        // Check that user is in the required role.
        bool isAuthorised = (_requiredRole == UserRoleTypesEnum.None || (userSession != null && userSession.Roles.Contains(_requiredRole)));

        if (!isAuthorised)
        {
            logger.Warn("Not authorised for " + args.Method.Name + ".");
            throw new UnauthorizedAccessException();
        }
        else if (userSession != null)
        {
            Thread.CurrentPrincipal = new MyPrincipal(userSession);
        }
    }

    private UserSession GetUserSession()
    {
        if (_serviceAuthToken != null)
        {
            string sessionID = _serviceAuthToken.GetSessionID();

             if (!sessionID.IsNullOrBlank())
             {
                 return _userSessionDataLayer.GetForSessionID(sessionID);
             }
         }

         return null;
     }
}

I have a singleton class setting up the Ninject kernel:

public class MyKernel
{
    public static StandardKernel Kernel { get; set; }

    static MyKernel()
    {
        Kernel = new StandardKernel();
        Kernel.Bind<IServiceAuthToken>().To<ServiceAuthToken>();
        Kernel.Bind<UserSessionDataLayer>().To<UserSessionDataLayer>();
    }
}

In my WCF service I use the PostSharp attribute as below:

[AuthoriseAndAudit(UserRoleTypesEnum.Operator)]
public JSONResult<bool> IsAliveAuthorised()
{
   return new JSONResult<bool>() { Success = true, Result = true };
}

And in my unit test I'm using RhinoMocks to try and mock the two DI properties in the attribute.

 [TestMethod]
 public void IsAliveAuthorisedIsAuthorisedTest()
 {
     var mockServiceAuthToken = MockRepository.GenerateStrictMock<ServiceAuthToken>();
     mockServiceAuthToken.Stub(x => x.GetSessionID()).Return("x");
     var mockUserSessionDataLayer = MockRepository.GenerateStrictMock<UserSessionDataLayer>();
     mockUserSessionDataLayer.Stub(x => x.GetForSessionID(Arg<string>.Is.Anything)).Return(new UserSession());

     MyKernel.Kernel.Bind<ServiceAuthToken>().ToConstant(mockServiceAuthToken);
     MyKernel.Kernel.Bind<UserSessionDataLayer>().ToConstant(mockUserSessionDataLayer);

     var service = new MyService();
     Assert.IsTrue(service.IsAliveAuthorised().Result);
}

The issue I have is the mock objects in the unit test are never ending up being set as the properties on the attribute. What am I doing wrong or conversely is there a better way to do unit testing on a PostSharp attribute? Also bearing in mind I really want to minimise the use of the Ninject DI to the bare minimum.

Answer 1

Instead of using the [Inject] attribute on your properties, redefine them like this:

    public IServiceAuthToken _serviceAuthToken { get { return _kernel.Get<IServiceAuthToken>(); } }

    public UserSessionDataLayer _userSessionDataLayer { get { return _kernel.Get<UserSessionDataLayer>(); } }

Also, in your test method you need to re-bind (note also that you were using the concrete type ServiceAuthToken in the first bind instead of the interface IServiceAuthToken):

MyKernel.Kernel.Rebind<IServiceAuthToken>().ToConstant(mockServiceAuthToken);
MyKernel.Kernel.Rebind<UserSessionDataLayer>().ToConstant(mockUserSessionDataLayer);