In the past week, I have been busy getting the unit tests working. Porting the tests over to NUnit was easy enough - just a lot of search and replace, and the results compiled succesfully. Running the tests, however, required some modifications to the core code. The gist of the changes was to be able to inject configuration values, which are available in the .NET runtime, but not necessarily so at times when NUnit is running.
Usually we would put these values in through a mocking mechanism (e.g. NMock2 - which is what I m using). But the Umbraco Web App contains a long static chain, which NMock cannot deal with. An option would have been to use TypeMock - but TypeMock is quite pricey, and in my opinion would have created a high entry price for contributing to the source code and tests.
Having had a quick perusal of the tests, it seemed that the easiest approach was to Interface out the .NET 'ConfigurationManager' class, then using the facade pattern create a couple of derived classes - one for testing and one for live use. To break the static chain, I replaced all references to 'ConfigurationManager' with a Singleton that instantiates the required ConfigurationManager class through dependency injection. This approach kept the changes to the original source to a minimum (hence, minimised the possibility of introducing bugs), but required the additionof the new ConfigManager classes. The approach is quite standart. At some point, it would be nice to revisit the long static chain - and make it non-static, e.g. initialize in global.asax - but that would require pretty big changes.
In sum, using this approach I can make the unit tests pass. At present some units are passing, and I am working through the remaining ones.