Exploring the Bug Investigation Techniques of Intermediate Student Programmers

Bug investigation – testing and debugging – is a significant part of software development. Ineffective practices of bug investigation can greatly hinder project development. Therefore, we seek to understand bug investigation practices among intermediate student programmers. To this end, we used a mixed-methods approach to study the testing and debugging practices of students in a junior-level Data Structures course with 3–4 week long projects. First, we interviewed 12 students of varying project performances. From the interviews, we identified five techniques that students use for both testing and debugging: 1) writing diagnostic print statements, 2) unit testing, 3) using source-level debugger, 4) submission to online auto-grader, and 5) manual tracing. Using the Grounded Theory approach, we developed four hypotheses regarding students’ use of multiple techniques and their possible impact on performance. We used clickstream data to analyze the level of use of the first four of these techniques. We found that over 92%, 87%, and 73% of the students used JUnit testing, diagnostic print statements, and the source-level debugger, respectively. We found that the majority of the students (91%) used more than one technique to investigate bugs in their projects. Moreover, students who used multiple techniques had overall better performance in the projects. Finally, we identified some ineffective practices correlated with lower project scores. We believe that the findings of our research will help understand, characterize, and teach better practices of bug investigation.