Jamal Hansen writes some tests:
I once had a query that ran fine for months. Then someone added a column to the source table and a
SELECT *downstream started returning unexpected data. The query didn’t error. It just silently gave wrong results. A test would have caught it immediately.Schema changes break queries silently. Refactoring a CTE can shift results in ways you don’t notice. New data patterns expose assumptions you didn’t know you made. SQL deserves the same testing discipline as the rest of your code, and Python makes it straightforward.
PyTest, the library Jamal uses here, is one of my favorites for this kind of work. You can build up tests without a lot of ceremony and it’s pretty easy to deal with for most use cases.