I have just pushed to the docs topic branch a complete rewrite of the recommendations for TEST-OP.
I think this rewrite better maintains abstraction, because the testing methods are on the test library, rather than on the library to be tested. I also explained why one should have a separate test library.
I have abandoned any attempt at ASDF 2 compatibility, also. It makes the presentation too cumbersome and twisty.
I welcome inspection of this changed definition and suggestions for improvement.
Best, r