Bug 31333: Unit tests

Bug 31333: Unit tests

Test plan:
1. Run tests (Categories.t has been updated by me, and I suggest running
Suggestions.t to confirm it still passes):

sudo koha-shell kohadev
prove t/db_dependent/Koha/Patron/Categories.t
prove t/db_dependent/Koha/Suggestions.t

Sponsored-by: Catalyst IT, New Zealand
Signed-off-by: Rhonda Kuiper <rkuiper@roundrocktexas.gov>
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>