Evaluating advantages of test driven development: a controlled experiment with professionals

Test driven development (TDD) is gaining interest among practitioners and researchers: it promises to increase the quality of the code. Even if TDD is considered a development practice, it relies on the use of unit testing. For this reason, it could be an alternative to the testing after coding (TAC), which is the usual approach to run and execute unit tests after having written the code. We wondered which are the differences between the two practices, from the standpoint of quality and productivity. In order to answer our research question, we carried out an experiment in a Spanish Software House. The results suggest that TDD improves the unit testing but slows down the overall process.