The obvious production implementation would be as a module that can be required. I'm not sure that spurious function call, which defines a slew of functions that are on GLOBAL anyway, is the way to accomplish something a little bit like that in the context of a kata.

Is it very much out of the box to ask the user for namespaced functions, after which the tests are run as they are now within a with block? That seems to be a more reasonable approximation of the above mentioned implementation. ( This depends on the testing framework not requiring strict code. I don't know if it does. )

I may be overlooking a more simple, obvious way to do this. But defining umpteen functions on GLOBAL just does not seem the best way. What better ways are there?