It's also useful to check the function doesn't crash. I use hypothesis to test a DB abstraction, and it often caught bugs in edge cases I didn't consider: time

It's also useful to check the function doesn't crash. I use hypothesis to test a DB abstraction, and it often caught bugs in edge cases I didn't consider: timestamps/timezones too large, strings containing null bytes, etc. These would be caught by the tests generated by hypothesis-auto.