Use `selectn` rather than self-rolled `getObjectProperty`

Also fixed broken folders push tests after notification counts got merged in
Merge branch 'notification-counts-follow-up' of https://github.com/simong/Hilary into notification-counts-follow-up
Fix failing notification tests
Made test signatures more consistent
Merge branch 'notification-counts-follow-up' of https://github.com/simong/Hilary into notification-counts-follow-up