Self-Admitted Technical Debt and comments’ polarity: an empirical study

Self-Admitted Technical Debt (SATD) consists of annotations—typically, but not only, source code comments—pointing out incomplete features, maintainability problems, or, in general, portions of a program not-ready yet. The way a SATD comment is written, and specifically its polarity, may be a proxy indicator of the severity of the problem and, to some extent, of the priority with which it should be addressed. In this paper, we study the relationship between different types of SATD comments in source code and their polarity, to understand in which circumstances (and why) developers use negative or rather neutral comments to highlight an SATD. To address this goal, we combine a manual analysis of 1038 SATD comments from a curated dataset with a survey involving 46 professional developers. First of all, we categorize SATD content into its types. Then, we study the extent to which developers express negative sentiment in different types of SATD as a proxy for priority, and whether they believe this can be considered as an acceptable practice. Finally, we look at whether such annotations contain additional details such as bug references and developers’ names/initials. Results of the study indicate that SATD comments are mainly used for annotating poor implementation choices (≃ 41%) and partially implemented functionality (≃ 22%). The latter may depend from “waiting” for other features being implemented, and this makes SATD comments more negatives than in other cases. Around 30% of the survey respondents agree on using/interpreting negative sentiment as a proxy for priority, while 50% of them indicate that it would be better to discuss SATD on issue trackers and not in the source code. However, while our study indicates that open-source developers use links to external systems, such as bug identifiers, to annotate high-priority SATD, better tool support is required for SATD management.