Testing the Fortuna random number generator?
Perhaps obvious, but couldn't you download other implementations, design a test set of your own, and run it through multiple implementations to verify the same results?

There are these implementations:


http://sourceforge.net/projects/fortunaprng/
https://github.com/dlitz/pycrypto/tree/master/lib/Crypto/Random/Fortuna


If system entropy is an issue, you might be able to tweak all implementations to fudge the updates to be equal.