Accurate method and variable tracking in commit history.

Tracking program elements in the commit history of a project is essential for supporting various software maintenance, comprehension and evolution tasks. Accuracy is of paramount importance for the adoption of program element tracking tools by developers and researchers. To this end, we propose CodeTracker, a refactoring-aware tool that can generate the commit change history for method and variable declarations with a very high accuracy. More specifically, CodeTracker has 99.9% precision and recall in method tracking, surpassing the previous state-of-the-art tool, CodeShovel, with a comparable execution time. CodeTracker is the first tool of its kind that can track the change history of variables with 99.7% precision and 99.8% recall. To evaluate its accuracy in variable tracking, we extended the oracle created by Grund et al. for the evaluation of CodeShovel, with the complete change history of all 1345 variables and parameters declared in the 200 methods comprising the Grund et al. oracle. We make our tool and extended oracle publicly available to enable the replication of our experiments and facilitate future research on program element tracking techniques.