Agile Defect Prevention | Part 2

Continuation of https://davidjellison.wordpress.com/2011/09/23/agile-defect-prevention/

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.