Locks in use

Basically what is in use? A lock on a practice door holding it closed? A lock that is attached to a pipe in my basement ? Alock on a door I've taken away from the frame? A padlock thar is intact and locked?

Because these are all technically installed and locked.

Can I not ensure the locks in my Home are adequate for the task by opening the door and checking the lock that currently serves no purpose, or should remove 2 screws and pick it standing beside the empty hole?

Rules need to be exact in language and description if you want them to be followed. A lock is a lock when it's secured and in use, so tell me when is a closed lock not in use?