ML-Based Test Case Prioritization: A Research and Production Perspective in CI Environments

Test case prioritization (TCP) is essential for improving testing efficiency in large-scale continuous integration (CI) environments by reducing feedback time and efficient resource usage. Machine learning (ML) has shown promise in enhancing TCP, however, demonstrating its effectiveness in production environments remains a challenge. Using the IBM Open Liberty dataset, we developed and validated an ML-based TCP framework, showing how we identified the best-performing model step by step-from feature extraction and model training to hyperparameter tuning. After validating the framework in a research setting, we deployed it in IBM's live production system. The practical implications of this study are as follows. The production results closely mirrored the research outcomes, with models trained on recent data consistently outperforming older models and non-prioritized approaches. Specifically, prioritized builds achieved a mean Average Percentage of Faults Detected (APFD) value 50% higher than that of non-prioritized builds, leading to a substantial improvement in early fault detection. The consistent improvement of models trained on newer data (M-2023) over those trained on older data (M-2022) underscores the importance of regular model updates in maintaining optimal performance. This paper comprehensively compares research and production data, illustrating how our ML-driven TCP framework ensures optimal performance and detailing the steps necessary for successful implementation in dynamic CI environments.