Hmm. One thing you can do is keep a log of the errors you fixed when you were testing your patch (and the state of your patch that had the error). Then, sit down with someone and go over that log to try to extract tests from the bug descriptions. It's usually not something you can do alone until you gain some experience, and have insight into where your blind spots are so you can write tests to probe them. That said, it's definitely something that (IMO) is worth discussing, so a dw_dev entry like foxfirefey suggested is probably a good idea.