I listed "a" set of test parameters, ultimately we will each have to suit ourselves though. Two, ten shot groups from a clean barrel at 100 yards for rifles with known-good load. Allow to sit a few days or weeks, then two, ten-shot groups again without touching the barrel. Pistols can be tested at whatever range you like, however many shots you like.
If testing the soap lubes with 30% or higher sodium stearate content, you might consider the need to adjust the load for the lube because it DOES change the friction characteristics of the bore significantly.
Gear