Improving the effectiveness of spectra-based fault localization using specifications

Fault localization i.e., locating faulty lines of code, is a key step in removing bugs and often requires substantial manual effort. Recent years have seen many automated localization techniques, specifically using the program's passing and failing test runs, i.e., test spectra. However, the effectiveness of these approaches is sensitive to factors such as the type and number of faults, and the quality of the test-suite. This paper presents a novel technique that applies spectra-based localization in synergy with specification-based analysis to more accurately locate faults. Our insight is that unsatisfiability analysis of violated specifications, enabled by SAT technology, could be used to (1) compute unsatisfiable cores that contain likely faulty statements and (2) generate tests that help spectra-based localization. Our technique is iterative and driven by a feedback loop that enables more precise fault localization. SAT-TAR is a framework that embodies our technique for Java programs, including those with multiple faults. An experimental evaluation using a suite of widely-studied data structure programs, including the ANTLR and JTopas parser applications, shows that our technique localizes faults more accurately than state-of-the-art approaches.