Testing datetimeDiff() passing dates

We found an issue in our driver had an issue when passing a date datetimeDiff() instead of a datetime. Even though it is fixed, we'd like to write a test to cover that scenario.

What would be a good test to base this on?

check metabase/date_time_zone_functions_test.clj at master · metabase/metabase · GitHub

I forgot to mention I tried to adapt datetime-diff-base-test() to no avail