There is nowhere in standard Moodle (except the unit test) that will actually use the problematic situation at present (unless you really want to configure MongoDB with the extended mode setting, which I think is not really necessary to test this). I suggest the following tests are sufficient: Automated testing: Confirm that the unit tests pass. The newly-added test function covers this behaviour and did fail before this fix. Manual testing: Visit Site administration / Developer / Purge caches and click Purge all caches ; this ensures course modinfo will be rebuilt on the next step. Visit a course page - this will confirm that modinfo cache (which uses the locking mechanism) has not been broken by the change.