From parent T184544: [EPIC] Write integration tests for ReadingLists extension:
From the coverage's dashboard is also possible to see that some core classes need unit tests too.
https://doc.wikimedia.org/cover-extensions/ReadingLists/src/index.html
- HookHandler (0%) (Not really testable)
- ReverseInterwikiLookup (0%)
- Utils.php (57.69%)