"...testing something without ....": That's correct. It's called a pragmatic (or "experimental") approach.

You're asking a vastly broad question (and one whose answer could be assumed -- in a perfect world, that is -- to have been addressed in documentation, bug reports, etc. by those whose efforts go into Unicode standards and development: However, as has occasionally been the case in other contexts, 'ain't nuttin' guaranteed perfect!'

If your latest response is an indication, you seem to be rejecting a method that puts your work back on your back. Downvoted.