Glad you found this article interesting. I have also found myself transferring WPF patterns to WinForms, as you know we use MVVM for our grid controls. (However, MVVM is really just a new and sexy name for the Martin Fowler’s presentation-model pattern!)

Regarding unit testing, I had this same discussion with Gergely yesterday, I don’t believe in unit testing UI code.

With the example I use in this blog post, the ViewModel is being used as a means to format a phone number, something that is hard to achieve with the tools available in the WPF framework. The important point to me is that this is ‘formatting’, i.e. pure presentation.

Sure, you could try and unit test it, however, what if someone screws up the positioning of the controls, or the font? your tests would pass, but the UI would be all wrong! In my opinion UIs should be tested by humans.

(Having said that, I probably would unit test the parts of the code which manipulate the phone number and extract its component parts – however, I would make this a separate, non UI-centric unit!)

Regards, Colin E.

I tried applying this pattern directly to WinForms (given the projects I work with currently are WinForms) and it comes up quite nicely.

I do share Brian Genisio’s concern about unit testing, but its an interesting point about not coupling the View and ViewModel to any business objects – "decompose it into a number of re-usable controls, each containing mini-ViewModels". I guess you could introduce an interface for business objects to use, but that adds complexity and defeats the purpose of your article.

Think miniViewModel is something I’ll add toolbox. Thanks Colin.

Thanks for your feedback. Personally I think the problem (if it is indeed a problem!) is that WPF (and Silverlight) is in itself both a powerful and complex framework. You really need to learn how it works, and DataContext inheritance is part of this learning process.

Regards, Colin E.