Visual Studio Unit Testing of Windows Forms

This is all well and good for regular application unit testing ... but if you are building user controls that need unit tests for the control behaviors and states, it needs a unit test framework too. NUnitForms might be the answer for you - personally I need to check it out myself.

I use the Passive View architecture as detailed here http://martinfowler.com/eaaDev/PassiveScreen.html

Basically move all your code in the forms to a separate class called the xxxUI. The form then implements a IxxxUI interface and expose anything that the xxxUI class needs. You can probably simplify things and aggregate dealing with several controls into one method.

The flow then goes The USER click on a button. The button calls a method on the corresponding UI class. Passing any needed parameters. The UI Class method modifies the model. Then using the interface updates the UI.

For unit testing you have test or dummy classes implement the interfaces and register themselves with the UI Classes. You can have these test classes fire any type of input and respond accordingly. Typically I have sequence lists that do thing in a precise order. (Tap A, click this, scroll that, then Type B, etc).

You would need to refactor the UI so that UI does not need any unit testing. UI should contain minimum or no business logic. There are many patterns that deal with this issue. Martin Fowler has a very good article that explains a lot about these patterns: http://martinfowler.com/eaaDev/uiArchs.html

There is a small chapter in the Refactoring book by Martin Fowler that talks about refactoring the non testable UI. You could also read Working Effectively With Legacy Code.

Note: There are tool that could be used to automate the UI testing. SilkTest comes to my mind. But I would not use them if possible.