Fault localization and repair are time-consuming and tedious. There is a significant and growing need for automated techniques to support such tasks. Despite significant progress in this area, existing fault localization techniques are not widely applied in practice yet and their effectiveness varies greatly from case to case. Existing work suggests new algorithms and ideas as well as adjustments to the test suites to improve the effectiveness of automated fault localization. However, important questions remain open: Why is the effectiveness of these techniques so unpredictable? What are the factors that influence the effectiveness of fault localization? Can we accurately predict fault localization effectiveness? In this paper, we try to answer these questions by collecting 70 static, dynamic, test suite, and fault-related metrics that we hypothesize are related to effectiveness. Our analysis shows that a combination of only a few static, dynamic, and test metrics enables the construction of a prediction model with excellent discrimination power between levels of effectiveness (eight metrics yielding an AUC of .86; fifteen metrics yielding an AUC of.88). The model hence yields a practically useful confidence factor that can be used to assess the potential effectiveness of fault localization. Given that the metrics are the most influential metrics explaining the effectiveness of fault localization, they can also be used as a guide for corrective actions on code and test suites leading to more effective fault localization.

Developing and integrating software in the automotive industry is a complex task and requires extensive testing. An important cost factor in testing and debugging is the time required to analyze failing tests. In the context of regression testing, usually, large numbers of tests fail due to a few underlying faults. Clustering failing tests with respect to their underlying faults can, therefore, help in reducing the required analysis time. In this paper, we propose a clustering technique to group failing hardware-in-the-loop tests based on non-code-based features, retrieved from three different sources. To effectively reduce the analysis effort, the clustering tool selects a representative test for each cluster. Instead of analyzing all failing tests, testers only inspect the representative tests to find the underlying faults. We evaluated the effectiveness and efficiency of our solution in a major automotive company using 86 regression test runs, 8743 failing tests, and 1531 faults. The results show that utilizing our clustering tool, testers can reduce the analysis time more than 60% and find more than 80% of the faults only by inspecting the representative tests.