Analysis of Test Driven Development on sentiment and coding activities in GitHub repositories

This paper studies the relationship between Test Driven Development (TDD), productivity and developer sentiment in order to assess the impact of TDD on software development. We used a set of 256572 Java repositories archived from GitHub in September 2015 and made available through the Boa language and infrastructure. This research found that of these repositories, 9537 could be classified as using the TDD methodology. After obtaining these repositories we compared them to an equivalently sized set of control repositories. In general those repositories practicing TDD had fewer commits and a faster median rate of committing than did their control counterparts. We also found that TDD repositories generally contained fewer bug fixing commits. Finally, sentiment analysis was performed on both sets of repositories and it was determined that TDD repositories have a significantly (p-value 3.857e-12) more positive sentiment in comparison to the control repositories.