Long-Term Effects of Test-Driven Development A Case Study

Test-Driven Development (TDD) is one of the most widely debated agile practices. There are a number of claims about its effect on the software quality and team productivity. The current studies present contradicting results and very little research has been performed with industrial projects, which have used TDD over an extensive period of time. This paper is reporting the long-term effects on a three year-long application of TDD in a Nokia Siemens Networks team. We present qualitative findings based on interviews with the team members. We conclude that TDD has been found to improve the team confidence in the code quality and simplify significantly the software maintenance. The examined team did not notice any significant negative effects over the long-term TDD application and is eager to continue improving the practice application. The authors suggest that results bear direct relevance to the industry and academia. Further research avenues are indicated.