The idea is that this TypeTuple be available to all unittest blocks so that they (and any dependent modules) can all do similar foreach() runs over all the available set of RNGs.  I have a further patch in the pipeline which will extend that kind of testing to all std.random unittests, but I've withheld it for now as it's probably a good idea to wait until after pull request #1357 lands.

I could move the TypeTuple inside the randomShuffle unittest block for now and move it out again when the later patch is submitted -- your call. :-)