ATK has built-in test support for a while now. But until now this didn't include support for adding, updating and/or removing test data in such a way that the development/production database isn't littered with test data. You can make use of the mock database class, but then you can't really test if the query you wrote actually works the way it's supposed to work. And you can ofcourse remove the test data in your test by writing the necessary code to do so, but this means a lot of extra work.

As of today there's a third option, you can make use of ATK's built-in test database support.