On top of the below, the tests are pathetically weak: see this and this. It doesn't even check if GivesTo is a person.

The actual test consists of one fixed test case.

This isn't really a kata, this is a puzzle question. It requires the user to find the solution of the given question. It isn't suitable as a kata unless the input is generalized.

Fun small-scoped kata. It's really is one of those challenges that you run across in practice.

Very tiny improvement: fix the typo in test_it_wont_assign_people_to_who_they_gifts_to_last_year to test_it_wont_assign_people_to_who_they_gave_to_last_year.