Agile Defect Prevention
I recall a day in the late ’90′s when assessing readiness for deployment of an application at Kodak after a several month long release cycle having 3,000 deferred defects. WOW! I can’t believe that was acceptable at that time, but in long waterfall release cycles that was the norm at the time. How can you manage defects like this? Today, this is unacceptable. The idea of “deferred defects” has always bothered me in software development. So, what can we do about this?
Along comes agile software development cycles where a defect backlog is an anti-pattern (No Bugs). The idea is that through continuous integration, unit tests, early inspection, and regression tests, your team finds problems as they are introduced. This is great in theory, but how do we manage the inevitable defects that we can’t get to and is an acceptable risk to meeting business requirements, and those defects that will come in from the field as support requests to fix? My approach to managing this is to focus on “defect prevention” as opposed to “defect tracking.”
Defect prevention, really? …is that possible? Imagine counting defects on your two hands. How can we accomplish this? Efficient agile organizations focus on defect prevention rather than downstream defect discovery. A culture of defect prevention includes separating “work in process” defects (WIP Defect) from “escaping” defects (Defect) to minimize defect management that escape beyond the sprint that features are developed in. This results in a much smaller defect backlog to manage and dramatically increased customer satisfaction. Agile is not just about releasing more often, but also with complete and tested features. So, we need to treat defects found in development as actionable sub-tasks of the feature work item. If we treat these WIP Defets as sub-tasks and acceptance criteria of completing the development tasks, then we are not introducing them to the field and not adding to the project team backlog as technical debt.
Escaping defects should then be treated as ranked backlog work items, along with other project work items. They should be prioritized high enough to resolve them within the next sprint or two and not accumulate a growing backlog. Watch the defect backlog as part of the project metrics. A growing defect backlog is a key indicator that the team is taking on more new work than it can handle. It may also be a key indicator that the team is operating as a “mini-waterfall” project, rather than a agile project, requiring more collaboration between Dev and Quality Engineers and early testing. Drop the number of new items the team works on until the escaping defects are well managed or eliminated.
When a WIP Defect must exist past the completion of the parent development task, then promote it to a Defect and place it in the backlog in rank order with other work. However, whenever possible the team should heavily scrutinize this practice and opt to hold delivery of the feature until the WIP Defects are complete. Also, a Defect in the backlog could be demoted and attached to an active development task to include it in the acceptance criteria for that task.
At Constant Contact, we now have our defects in the same tool (Jira/GreenHopper) that we manage new feature work, such that defects are in the same project and iteration backlogs. This provides greater visibility to the product owner ranking the work and the team implementing the work.