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Articles : Using Customer Tests to Drive Development
on 2007/9/7 2:56:36 (2545 reads)

Building on CTDD

Despite the success whenever we write customer tests first, we can become complacent or get in too much of a rush and neglect this practice. Recently we had a fairly simple story (we thought) that only a couple of internal customers would use. We did write test cases in advance of coding, but as the internal customers were always busy and we thought we understood it well, we neglected to go over the test cases with the customers. After deploying to production, one of the customers tried to use the new functionality, and found it was not at all what he wanted. Now we have an unhappy customer, who has to write new stories to get what he wanted in the first place.

When our business was at its peak time of year and we were all busy, sometimes the tasks to automate tests got pushed towards the end of the sprint, making a time crunch for testing. We made ‘writing FitNesse fixtures early’ a team goal for a few iterations, until this became a habit. We use a task board to monitor progress for each story, and if the ‘write FitNesse fixtures’ task doesn’t move into the Work In Progress column by a certain point, someone will ask about it during the standup meeting.

Our company has experienced the benefits of CTDD, and has made its use a company-wide goal. Although our company is quite small (only around 20 employees), we have a product owner (who is also our ScrumMaster) who works with our team full time. In addition, a senior vice-president who is the most knowledgeable about the domain has been given the time and directive to work closely with our engineering team. He writes test cases for at least one story in advance of each iteration. We have a new goal to finish high-level test cases for all stories of an iteration by the fourth day of the two-week iteration. This new commitment to CTDD, along with our commitment to early test automation, makes us talk to each other when we need to – before and during coding.

Other Success Stories

Our team has drawn inspiration from other teams’ use of CTDD. Richard Watt and David Leigh-Fellows presented their techniques in "Acceptance Test Driven Planning" at XP/Agile Universe 2004. They use a practice they call "Getting our stories straight". QA works with customers at end of each iteration to write tests for next. They use these tests as a planning tool to guide estimation and task breakdown. It’s not Big Up-Front Design (BUFD), but a "just right" amount of process.

Another source of ideas was an article in Better Software Magazine (July/August 2004) by Tracy Reppert called "Don’t Just Break Software, Make Software". She details the story test-driven development used by Nielsen Media Research. Joshua Kerievsky, a pioneer of STDD, says it "helps teams obtain the necessary amount of story details before writing code." He also notes, "Following story test driven development clearly enabled me to produce designs I simply would not have anticipated."

What if I’m not On an Agile Team?

"It all sounds great", you say, "but I’m stuck in a traditional waterfall process. How can CTDD benefit my project?" After being on XP teams for a couple years, I had to go back to the "dark side" and work on a less agile team for a time. They wanted to implement agile development, but couldn’t quite make the commitment. I asked the managers where they felt the most pain on projects. They immediately responded that requirements were their biggest problem. On some projects, too much time was spent gathering requirements, which were changed and out of date right away and thus useless. On the rest, the programmers were forced to start coding with no requirements at all.

"What if we write customer tests ahead of development?" I proposed. They agreed to try it, and our results were good. We were able to get people on the business side working more closely with us, and the programmers appreciated having some direction before they started writing code. Even though the programmers didn’t assist directly with test automation (all automation was done by my test team), writing customer tests first did help guide development. The resulting software was closer to the customer’s requirements. This success led to trying more agile practices on ensuing projects, again with good results. Writing tests ahead of development is something a test team can implement without a major effort, it just requires a bit of cooperation from the business side. It can change a team’s culture just a bit, so that it may be open to more practices that will improve development, and improve life for the developers!


Originally published in the Summer 2005 issue of Methods & Tools 

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