At the Scrum Gathering in May, Mike Cohn gave some good advice about testing in software that applies to all types of Agile Work. A very important Agile Work Practice is Test-Driven Work. If you are applying agile to an existing endeavor, there may be a lot of work already completed which does not have tests in place. This is a testing debt: eventually you will have to pay the principle down (build tests) or you will keep paying the interest (fix quality problems).
1. Start by creating tests that are easy. This is the “low-hanging fruit” and it gives the team a sense of accomplishment and progress against what may be a very large and difficult (but necessary) task. This can be done in such a way that it creates a framework that makes the creation of future tests easier.
2. Add to all new work the creation of tests. This is the move to test-driven work. At this point, your testing debt will now be growing smaller as a percentage of the overall amount of work. This standard must become second-nature to the team.
3. Once all new work is being done in a test-driven fashion, it is possible to start paying off the testing debt principle. The team sets aside a small amount of extra time to build tests for work that is already “complete”. It is important to focus on building tests for the parts of the work that are most likely to need the tests.
For software, the book Test Driven Development: By Example by Kent Beck is an excellent introduction. I would like recommendations for books and web resources for testing and quality in other fields. Please email suggestions to email@example.com.