Independent test teams

The agileprojectmanagement discussion group on yahoo has a recent thread titled "Testing Sprint Advice" that caught my attention. (Note that you'll need to be a member of the group to follow the link.)

I believe the ultimate goal of agile testing/QA should be the complete and unambiguous definition of acceptance criteria. The ultimate manifestation of that would be executable requirements defined by the product owner. Of course the product owner would create these in collaboration with testers, and including developer input as appropriate.

There is often debate over whether test teams are more effective when they are independent from the development effort or when they actively collaborate with developers. I personally believe the collaborative approach is better. If the product owner and QA collectively define unambiguous acceptance criteria, then the developers are usually in the best position to automate the validation of those criteria through automated tests of various kinds. Since it's hard to formally define every single acceptance criteria, testers can focus much of their effort on exploratory testing - which of course may leading to a better understanding of additional acceptance criteria.

Steven Gordan makes some great points in the post, arguing for the collaborative approach which I'll summarize below..

1. If the testers effectively come up with their own version of the requirements based on an "independent" understanding of the product, then inevitable disputes over the actual requirements for the iteration ameliorate much of the potential value of independent testing....

2. If the testers actively participate in the development of the acceptance criteria for the iteration, then where is the independence? If they are going to actively collaborate with the team and customers from day 0 of each iteration, everyone would be better off if they were actually part of the development team.

3. If the testers passively utilize the acceptance criteria for the iteration without actively voicing their independent opinion about what is missing from the acceptance criteria, then we get the worst of cases 1 and 2. The testing is not truly independent, yet what independence remains is not being leveraged to improve the acceptance
criteria.

Inevitably, independent testing finds problems later than
collaborative testing would.

Thanks to Steven for the great insight.