Test-Driven Development - Still a Promising Approach?

Test-Driven Development (TDD) has been regarded as a useful practice during the last decade as well in industry as in academia. It has been suggested to have several benefits in software development process. This paper is focused on the reported empirical research on TDD. A systematic literature review was conducted in order to analyze the current empirical evidence. Based on the review data, TDD may improve external code quality, but it also leads to increase in development time. However, there are a lot of contradictory results and it raises a question about the actual factors behind them. More systematic research, specifically controlled experiments and well reported case studies, is needed in order to better understand TDD.