[mpalme]

> So if Martin Fowler says that it is possible to use a service locator instead of DI in unit testing, then who are you to argue otherwise?

There are good arguments against a service locator - one of them is presented here: http://blog.ploeh.dk/2010/02/03/ServiceLocatorisanAnti-Patte...

Another argument again the service locator pattern is this: If you ask the locator for a service which has dependencies you have to resolve those dependencies yourself. So you need to know about the specific implemntation of this service interface which defeats the purpse. If you work around that, you end up with something that is pretty close to a DI container.