refs: https://github.com/TryGhost/Team/issues/626
- calculated settings are simplified settings (booleans) that are based on other settings or data
- they make it easier for us to determine what state features are in elsewhere in ghost e.g. admin and themes
- this duplicates some of the members config concepts in the settings service
refs: e68cb8b314
- a couple of months ago when improving the test coverage here I found some weird behaviour with falsey values
- turned out it didn't matter at the time because we didn't have any settings that are false
- with the introduction of calculated settings we will have: https://github.com/TryGhost/Ghost/pull/14766
- whilst building that, I found settings that should be returned as false were being returned as null
- fixing it in a separate commit to keep the work clean
refs: https://github.com/TryGhost/Ghost/commit/e68cb8b31
- I found that some of the places we use rewire are totally unnecessary
- Rewire seems to mess with coverage sometimes
- It's also a code smell in general so I've ripped it out where possible
- settings cache was appearing as untested because we use rewire!
- rewire was totally unnecessary in this case, so I removed it
- updated to 100% test coverage whilst there, including removing one unreachable branch
- commented some undesirable behaviour I found whilst trying to reach all branches
- I don't want to change the behaviour to return false correctly without having a reason beyond improving coverage
