Not much activity on here recently, must be stuff going on somewhere.

Anyway, I’ve been pondering the role of testing in an agile environment more and more recently as its something we need to get right. I’ve already touched on tester driven design in an earlier post.  Now I’d like to look at three basic concepts that may help us move on. The three concepts are:

1. Forget about test phases and replace with ‘user stories’
2. The coding, testing continuum for a user story
3. The roles in an agile team

The first concept is probably the most scary. Most teams are familiar with the Design, Code, Unit Test, Functionally verify, System verify approach to developing software. So the assumption is that in an agile environment you will still need an FV phase followed by an SV phase. This is what I want to challenge.

I’d like us to think of it more simplistically. We write some code, we do some testing. What code and testing we do should be clearly defined by the user stories that are driving the delivery. So, if for example we are delivering a new API, we would have user stories to describe how the API would be used in the single user environment (equivalent to FV type testing) and stories that describe how it might be used in a high load environment (equivalent to SV type testing). So the right type of testing still gets done, we are just driven by the user story deliveries rather than by the traditional test phases.

This then leads nicely into the second concept which I’ll cal the ‘code/test continuum’. When you have user stories as described above you’ll find that some have a large amount of coding and a relatively small amount of testing. (Delivering an implementation of an industry standard API that already has a conformance test suite would be a good example of this). At the same time you will also have user stories that have very little coding, but large amounts of testing required (using the API in a complex environment under heavy load for instance).

So the two extremes may be expressed like this.

CODE………test..

code….TEST…….

But in reality the user story can fit anywhere on the continuum.

This is an important step to realize, because I think traditionally use cases and user stories have been geared towards the functional or code end of the spectrum and we need to ensure that all aspects of a delivery are considered.

Now how do we deliver on this sort of continuum? Well that’s where my third concept comes in. The roles of the agile team. For too long we have had the split in roles between coders and testers. This has to change if we are to be more agile. What we need is skilled software engineers who are capable of coding and testing. If we had a one person project then  it is obvious that that one person would need to perform both roles. so why is it that when our project team s grow  we feel we have to split the roles across different people?

If you take an ideal sized project team (about 10) I’d expect to see a spectrum of people ranging from a small number of pure coders at one end to a small number of pure testers at the other, but with the bulk of the team sitting in the middle as ’software engineers’ who can switch roles depending on the needs of the user story. The team would morph with each delivery making much more effective use of the team’s resources.

I’ll be carrying on this thread as its close to my heart at the moment. Let me know your thoughts.

Tags: agile, SVT

This entry was posted on Friday, May 9th, 2008 at 12:00 by Jon Tilt. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.