Bugs and rework
One of the first questions I asked after we had started with Kanban for software development is what do we do when we find a bug? An item has made its way through the pipeline out of Development and into QA, the tester finds a bug so what to do. Should we move the story it relates to back to Ready for Development and if so wouldn’t that have an impact?
The advice I was given is that there are 3 scenarios, one is to raise a bug ticket and place it in the dev ready queue (waiting for it to be pulled) and mark the item it relates to as blocked, another is to stop the line and fix the issue, the third is to have an emergency queue for items such as bugs.
Corey Ladas stated that one way or another, buggy work-in-process is still in process and counts against the total WIP limit. The only question is which part of the workflow gets stuck with a kanban token for rework…
http://leansoftwareengineering.com/2007/11/25/accounting-for-bugs-and-rework/
David Anderson’s conclusion is that leaving the original Story/MMF/Feature in test is generally the hardest, take pain earliest solution. This is the harder approach. It treats the bugs like a process failure that must be attended to immediately.
Moving it back into Ready for Development allows things to keep flowing but at the cost of increased WIP, longer lead times and additional regression effects from coding against the defective code.
Our team has chosen the latter approach for now.
