Predicting bugs in software code changes using isolation forest

Identifying bug immediately when it is introduced can help improve the validity and effectiveness of bug fixing. Predicting bugs in software code changes makes such identification possible. Buggy changes, changes that introduce bugs into source code, can be viewed as anomalies relative to clean changes for that they are rare and irregular. Thus, anomaly detection techniques can be applied to buggy change prediction. Isolation Forest, which detects anomalies based on the hypothesis that the anomalies have the shortest average path length on the constructed random forest, has exhibited its good performance on anomaly detection compared to other anomaly detection methods. In this paper, we adopt it in predicting bugs in software code changes. Empirical study with eight practical open source projects are conducted to validate the effective of Isolation Forest in bug prediction in software code changes. Results of the empirical study show that compared to traditional classification methods used in literature, Isolation Forest can achieve better clean precision, buggy recall, buggy F-measure, AUC and Gmean.