Customer Test Driven Development (CTDD)

Test Driven Development has many advantages. Not only at unit test level, but also at functional, system and acceptance test levels which benefit from increased communication and collaboration.

Test Driven Developement (TDD) is a widely accepted agile development practice. It forces the programmer to think about many aspects of each feature before coding. It result in a safety net of tests, ensuring that refactored code maintains it functionality. TDD far outshines code produced in a traditional manner in quality and robustness.

With Customer Test Driven Development (CTDD) you drive projects with tests and examples that illustrate the requirements and business rules.

Customer tests are anything beyond unit and integration testing, they may include functional, system, end-to-end, performance, load, stress, security and usability testing. They show the customers that the delivered code meets their expectations.

How CTDD works

• split features into small, manageable chunks, known as 'stories'

• for each story, as a customer ask when you know this story is complete, in the form of tests and examples

• write tests that, when passing, prove the code meets the minimum requirements

Bring hidden asusmptions to the surface by writing customer tests before coding the features. It enables conversations between customers, testers and programmers. Customer tests don't replace direct communication between programmers and customers, they enhance it and document the story requirements. Commitment to early test automation, makes us talk to each other when we need to - before and during coding.

Make writing tests in advance a team goal for a few iterations, until it becomes a habit.

Are you stuck in a traditional waterfall process ? What if you write customer tests ahead of development ? It can change the team's culture just a bit, so that it may be open to more practices that will improve development.

From Using Cutomer Tests to Drive Development by Lisa Crispin in Methods & Tools Summer 2005

Book tip: Test Driven Development, by Kent Beck
This book follows two TDD projects from start to finish, illustrating techniques programmers can use to easily and dramatically increase the quality of their work. The examples are followed by references to the featured TDD patterns and refactorings.