Verifying a non-virtual method in base class is called using Moq

Question

This post requires the base class methods to be virtual: question link.

This does not work for me because the base class methods are not virtual (I did not write it and do not have source).

How do I mock out and verify the base class method was called if they are not virtual?

Last criteria - I am developing using Xamarin Studio on Mac. Moq works fine but other frameworks like TypeMock or JustMock (windows install programs) will not work.

Duplicate http://stackoverflow.com/questions/11738102/how-to-mock-non-virtual-methods — Juan Lopes, May 14 '14 at 17:41
@JuanLopes thanks for the link but since I am using Xamarin Studio on Mac, I don't believe those products will work. — IUnknown, May 14 '14 at 17:49

score 3 · Accepted Answer · answered May 14 '14 at 19:46

It is not possible. Because of the way Moq works, there is no chance Moq can mock a non-virtual method.

Are you mocking the class type YourClass directly, where YourClass derives from BaseClass, and BaseClass has this (public?) non-virtual non-static method that interests you? So your mock has type Mock<YourClass>, not Mock<IYourClass> where IYourClass is an interface?

Is it strictly necessary that you use BaseClass as a base class, rather than "composing" (having a field of type BaseClass insider your class)?

score 2 · Answer 2 · answered May 15 '14 at 09:26

As mentioned above, Moq can only mock virtual methods.
One possible end run is to wrap your un-moqable class in a proxy and use this proxy in your code.

public class MyUnMoqableClass {
    public string GetValue() {
        return "Hello World";
    }
}

public interface IMyUnMoqableClassProxy {
    string GetValue();
}

public class UnMoqableClassProxy : IMyUnMoqableClassProxy {

    private readonly MyUnMoqableClass _myUnMoqableClass;

    public UnMoqableClassProxy(MyUnMoqableClass myUnMoqableClass) {
        _myUnMoqableClass = myUnMoqableClass;
    }

    public string GetValue() {
        return _myUnMoqableClass.GetValue();
    }

}

It can be a bit (a lot) tedious if you have a large interface on the unmoqable class but does let one isolate the client code.

Yes this is what I ended up doing - I had to isolate the class that was unmock-able by moq. thanks. — IUnknown, May 15 '14 at 14:20

Verifying a non-virtual method in base class is called using Moq

2 Answers2