Machine Learning-based Test Case Prioritization using Hyperparameter Optimization

Continuous integration pipelines execute extensive automated test suites to validate new software builds. In this fast-paced development environment, delivering timely testing results to developers is critical to ensuring software quality. Test case prioritization (TCP) emerges as a pivotal solution, enabling the prioritization of fault-prone test cases for immediate attention. Recent advancements in machine learning have showcased promising results in TCP, offering the potential to revolutionize how we optimize testing workflows. Hyperparameter tuning plays a crucial role in enhancing the performance of ML models. However, there needs to be more work investigating the effects of hyperparameter tuning on TCP. Therefore, we explore how optimized hyperparameters influence the performance of various ML classifiers, focusing on the Average Percentage of Faults Detected (APFD) metric. Through empirical analysis of ten real-world, large-scale, diverse datasets, we conduct a grid search-based tuning with 885 hyperparameter combinations for four machine learning models. Our results provide model-specific insights and demonstrate an average $15 \%$ improvement in model performance with hyperparameter tuning compared to default settings. We further explain how hyperparameter tuning improves precision $(\max =1)$, recall ($\max =0.9633)$, F1-score ($\max$ $=0.9662$), and influences APFD value ($\mathrm{max}=0.9835$), indicating a direct connection between tuning and prioritization performance. Hence, this study underscores the importance of hyperparameter tuning in optimizing failure prediction models and their direct impact on prioritization performance.