Again it probably couldn't hurt to be more thorough and test a bunch of different orderings, though in this case the `assert` would be different for each ordering so I'd suggest multiple tests `test_related_list_sorted_by_most_recently_created()` etc.

I'm not sure how many different sort orderings are possible here. Either test them all, or if it's too many test the ones that seem likely to be the most commonly used.

Where is  the code that actually does the sorting? If it's further down (not in the action function itself) then it may be able to be unit-tested directly which might be faster, instead of calling the action function so many times in the test