BeAFix: an automated repair tool for faulty alloy models

BSTRACTThis paper describes BeAFix, a tool for automated repair of faulty Alloy models. The tool builds upon the Alloy Analyzer, the analysis tool for Alloy. It generates repair candidates by mutating a faulty Alloy model, and employs a bounded-exhaustive approach to traverse the space of repair candidates. Since BeAFix's mutation operators make the space of repair candidates to quickly grow, the tool supports some sound pruning techniques, that allow it to fix Alloy models with more than one faulty line or expression. Additionally, BeAFix does not require tests as a patch acceptance criterion. Although BeAFix supports tests as oracles, our tool is also able to leverage property-based oracles, which are more commonly found in Alloy models in the form of predicate satisfiability and assertion validity checks. A video demonstration of BeAFix can be found at https://youtu.be/5RG40SmlFXQ. The tool's binaries and further details about its usage, can all be found at https://sites.google.com/view/beafixevaluation/beafix. The tool is also available in a public archive at https://doi.org/10.5281/zenodo.5296466.