An empirical study on the removal of self-admitted technical debt

Technical debt refers to the phenomena of taking shortcuts to achieve short term gain at the cost of higher maintenance efforts in the future. Recently, approaches were developed to detect technical debt through code comments, referred to as Self-Admitted Technical Debt (SATD). Due to its importance, several studies have focused on the detection of SATD and examined its impact on software quality. However, preliminary findings showed that in some cases SATD may live in a project for a long time, i.e., more than 10 years. These findings clearly show that not all SATD may be regarded as 'bad' and some SATD needs to be removed, while other SATD may be fine to take on. Therefore, in this paper, we study the removal of SATD. In an empirical study on five open source projects, we examine how much SATD is removed and who removes SATD? We also investigate for how long SATD lives in a project and what activities lead to the removal of SATD? Our findings indicate that the majority of SATD is removed and that the majority is self-removed (i.e., removed by the same person that introduced it). Moreover, we find that SATD can last between approx. 18-172 days, on median. Finally, through a developer survey, we find that developers mostly use SATD to track future bugs and areas of the code that need improvements. Also, developers mostly remove SATD when they are fixing bugs or adding new features. Our findings contribute to the body of empirical evidence on SATD, in particular evidence pertaining to its removal.