Regression tests for GHSA-83g9-vjqf-2j5q, one per endpoint the advisory
named plus the delete and view paths found alongside them: a non-owner
gets 403 on every mutation of a public or shared rule, and the object is
asserted unchanged afterwards.
Also covers the parts that are easy to regress in the other direction:
shared users keep read access, a shared user deleting only revokes their
own access, unowned rules stay claimable, and children of invisible rules
answer 404 rather than 403.
SharedObjectPredicateParityTests asserts is_visible_to agrees with
SharedObjectManager across every owner/visibility/shared combination.
The manager builds a Q and the predicate tests an instance, so they
cannot share an implementation and can otherwise drift apart.
Herculino Trotta