This post originated from an RSS feed registered with Agile Buzz by Laurent Bossavit. Original Post: Whose bug is it anyway ? Feed Title: Incipient(thoughts) Feed URL: http://bossavit.com/thoughts/index.rdf Feed Description: You're in a maze of twisty little decisions, all alike. You're in a maze of twisty little decisions, all different. Latest Agile Buzz Posts Latest Agile Buzz Posts by Laurent Bossavit Latest Posts From Incipient(thoughts)

Here's a phrase which pushes a button for me: "It's your bug - you fix it." Heard it once in a real project. A recent newsgroup discussion, on the topic of "code ownership", brought it back.

OK, say everyone owns the code. Who owns bugs ? Surely it's important that, so to speak, "you own your bug" - individual ownership of at least one's mistakes. I agree that accountability is important. And I think it's best framed in terms other than "ownership".

Someone in the group writes bugs, the whole group has a problem. The harder you work to pin down who's to blame for the problem, the less chance you have of actually solving the problem.

So - how would accountability in the case of a bug work in an XP team ? Here's a possible scenario.

Phlip and I are just finished writing code for a new feature. We run the unit tests in our local sandbox, they all pass. We fetch the latest changes from CVS. Boom - suddenly some tests break. We look into it, and determine that the cause is some code Diana and Joe wrote yesterday makes some unwarranted assumptions.

Well, a bug is a big deal. Even a bug caught during development. So I walk up to Joe and his pair, and suggest we swap. (Diana is out today, but that's OK - Joe will know what happened.) Phlip will work with Jane on their task, while Joe comes over to help me fix the problem.

We discuss the "why" aspects first. I ask Joe to clarify what he was thinking. (Maybe I'm the one with a flawed assumption.) It turns out Joe has... interesting ideas about the inner workings of hash tables. I happen to know a few details about the contracts of equals() and hashCode() that help avoid this kind of issue.

Joe says he gets it, and writes a new test which shows he does indeed get it. We fix the problem and check in the fix.

Then we get to the important point. "Think you'll remember this? You've been bitten once, so maybe it'll stick..." But Joe wants to make sure: "I've got it now, but I feel like it could slip away. What I'll do is write a blog entry sometime this afternoon - if I can explain it to someone else I'll feel confident I won't get bitten again. And I'm sure there'll be someone to straighten me out if I only think I understand."

Ownership scorecard: who owns Joe's bug? The team does. Who owns the reason Joe made a mistake in the first place? The team does. Who owns the ability to make Joe a better coder? Joe does. ;)