I'm wondering if the OP understands the difference between outright lens sharpness and the lens' abilty to focus accurately.. Two entirely different thngs.. If one needs to test for outright lens sharpness one needs to focus manually, for the lens' ability to focus accurately, naturally one needs to use auto focus..
of course - there are scales for testing focusing as well.
When testing for sharpness, I always do one set manual focus, one set auto.
If for some reason the manual is sharper than the auto - then I'll do the focus testing.