Are there any automated unit testing frameworks for testing an in-house threading framework?
If your threads are built on OpenMP, you can use VivaMP for static checking.
But you want dynamic checking with unit tests. I'm not aware of any existing framework for this purpose. You could roll your own with one of the many unit test frameworks out there, but it would be hard to make it robust. Intel has a suite of parallel development tools that might be of interest, but I've never used them. They say that they can help with unit tests from within Visual Studio.
If you write a threading library you have to debug it yourself. Threading libraries aren't as general purpose as general purpose programs =D so you won't find a specific unit testing framework for your specific problem :D
After that disclaimer though. If you were running on Solaris / OSX or FreeBSD.... dtrace would make it trivial to unit test your library.