How do you Mock IUnityContainer?

Question

I'm trying to Mock the IUnityContainer using Moq 3.0

I'm getting a BadImageFormatException, but not when debugging. From the looks of it I'm not the only one that's ran into this problem.

here

And its a registered issue for Moq

here

I'm just curious if anyone has found a solution... closest I've found is a nice solution that uses RhinoMock by Roy Osherove

here

but I really like Moq! So I don't really want to have to switch to Rhino Mock but I will if I must

Thanks in advance!

Hampson

I'm having the same problem. Please let me know, if you found a solution to this. – Turnsole

So, are there no any solution still ? I've encountered the same issue with 3.1 Moq on 3.5sp1. – Objectify

Answer 1

You don't.

The only reason to mock the container is if you're passing it around. That's an anti-pattern.

Instead you want to compose the entire object graph at the application's entry point, or Composition Root.

If you need to create instances on the fly, use Automatic Factories.

For your tests, you can either construct the object under test and pass mock objects to the constructor or create a new container in the test and register mock objects with it.

Sternway

Agreed, made this question when I was young and nieve... I was also using IoC containers wrong. – Hampson

Answer 2

Do you need a full-blown mock object? Could you get by with simply implementing a Fake? I.e., implementing a test instantiation of the IUnityContainer interface and overriding the method that you need to interact with?

I've fallen into the trap more than once in thinking that since I have a mock object library, I should use it for isolating every dependency in my system. More often than not, doing something simpler gets me the results I want with much lower frustration levels.

Fritz

Why has been this comment down voted? Those who down voted pls care to leave a note so that others who follow will be able to learn better from SO. – Privation

Indeed. I upvoted the compensate. Creating a stub would solve the issue by avoiding it entirely (no use of Moq needed). It's a legit workaround and for those that voted this down, I'd encourage you to share why for the rest of the class. – Monarchal

Maybe Stackoverflowers don't like people with certifications? :) – Monarchal

Answer 3

Have you tried mocking UnityBaseContainer or UnityContainer instead of IUnityContainer, ala this post by Rory Primrose? He is dealing with RhinoMocks but because I think the issue is related to Moq's internal use of Castle, you may be able to solve the problem this way.

Jennifferjennilee

Answer 4

Because of this problem I don't mock IUnityContainer, I use a real instance of UnityContainer instead. It's not ideal but I can test registration by checking that the container can resolve types as appropriate.

You can mock and use IServiceLocator when you're using it to resolve types in your classes, or even better, use register a factory with the container and use that instead.

Ronda

Answer 5

Are you running this on Win x64 ? Have a look at this page. It clearly suggests.

This exception is thrown when the file format of a dynamic link library (.dll file) or an executable (.exe file) does not conform to the format that is expected by the common language runtime.

Also, found this blog entry which suggests changing the compilation flag from Any CPU to x86 might help the cause. http://filips.net/archives/2008/01/17/getting-badimageformatexception-in-64-bit-windows/

Edit:

Also have a look at this SO thread. Have a look within your Build Configuration Manager as well.

Toscanini

Answer 6

In order to be able to mock IUnityContainer's methods I would suggest mocking the methods on the interface rather than the extension methods. People usually want to mock Resolve<TFrom, TTo> extension method which is not possible using Moq. Instead of mocking this method try mocking the one which is basically doing the job:

Mock<IMyInterface> myInterface = new Mock<IMyInterface>(MockBehavior.Strict);
Mock<IUnityContainer> containerMock = new Mock<IUnityContainer>(MockBehavior.Strict);
containerMock.Setup(c => c.Resolve(typeof(IMyInterface), null).Returns(myInterface.Object);

Here I mocked the non-generic Resolve function because it will be actually called by the generic one.

Nickelsen