While setting up the CDash client "core-ubuntu-10.04" (compiling only MITK core) I found that mitkModuleTest (Core/Code/Testing/mitkModuleTest.cpp) depends on 5 modules that are built only for the purpose of testing.
When a project builts MITK with the CMake option MITK_MODULES_TO_BUILD option, mentioned test modules are only built when they are listed explicitly by the project which builds MITK.
This solution is not optimal because the "outer" project will not be interested in internal testing ideas and implicit dependencies. Each time these change, the project would need to take notice and update a couple of build environments or CDash clients.
I found that the simpler solution would be if the testmodules force themselves to be built explicitly, because they are always required for core testing.
Sascha, if you have a short look at my change and don't have objections, this could easily be integrated.