Posts Tagged ‘defect prevention’

Agile Defect Prevention | Part 2

June 24, 2012 2 comments

Continuation of

So you have your escaping defects under control and your team is looking to optimize further to become an elite agile team…what more can you do towards defect prevention? Just as WIP Defects (‘Work In Process’ Defects) are an antidote to Defects, TDD (Test Driven Development) is an antidote to WIP Defects. WIP Defects, although a great way to contain faults from getting into the customer hands, is still an anti-pattern to elite agile teams. These teams are test-infected and write more tests than application code, and catch most problems while authoring the application code.

Fine Craftsmanship

In an elite agile team, everyone writes and executes tests. Product Owners carefully craft use cases with well thought through acceptance criteria, and regularly validates both that the working application behaves as intended and is a delightful experience. Software Engineers write unit tests to assure solid code craftsmanship, performance tests in the sandbox to assure efficient basic application behavior, and manually inspect their user experience like a fine cabinetmaker inspecting the glide action of the drawers in the cabinet he is building. Quality Engineers work closely with the Product Owner to understand the intent of the features, and with the Software Engineer to understand the design and share test approaches, authoring and running tests along the way. Quality Engineers peer inspect tests with Software Engineers so that both are intimately familiar with the tests. Both Software and Quality Engineers regularly run unit and regression tests, and validate both performance and user experience in each context the application runs in.

Consider writing failing test cases instead of WIP Defects as a start down this path. I have found that Quality Engineers who are not use to developing tests early and conducting peer inspections of tests with Software Engineers, are initially uncomfortable by the idea of not writing defects. You need to document the defect somehow. The best documentation is the regression test and not a defect report. This will foster correcting the problem promptly as a failing test instead of a WIP Defect hand-off or scheduling an escaping Defect fix. Get into the habit of running regression tests for the feature being worked on often throughout the day in the sandbox environment, with visibility by the whole team, as part of the CI (Continuous Integration) cycle.

Measure cycle time and efficiency in defect prevention over defect counts. You may still need to track defect counts, fix/find rates, etc. (especially in a larger organization), however in an elite agile team these defect counts are so small that everyone in the team is aware of them. Defect prevention and correction are part of the cycle time to deliver the changes. Take the time to be clear on acceptance criteria, compatibility with standards and architecture, and stability of the code changes. Collaborate within the team such that progress on code design and development, and the tests to validate them, is well known. Elite agile teams write and execute the tests early and often that assure working software remains working.

Even in elite agile teams there are Defects that a found late in the iteration or are a larger problem than can be solved at the time of discovery to fix prior to declaring work done. This warrants creating an escaping Defect. The elite agile team carefully scrutinizes each escaping Defect for defect tolerance of the business and impact to the customer, before opting to let the escaping defect into the field. The intent of the agile life cycle is to add business value often, and in small enough iterations to foster continuous feedback, so it might be more important to deliver the change with the defect than delay delivery. An escaping Defect may survive past an iteration and still be held back to release into the field until fixed in another iteration.

Elite agile teams continually test with constant feedback of pass/fail results. There are no unknown failures left without attention to understanding the problem as it is introduced. Problems are corrected promptly and not let into the field for exposure to customers. The whole team is aware of test status through continuous integration practices. There are very few, if any, known defects in the field.

Agile Defect Prevention

September 23, 2011 1 comment

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?

No BugsAlong 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. constraining escaping defects to what fits on your two handsHow 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.

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