Don’t forget to change these functions! recommending co-changed functions in modern code review

Context:

Code review is effective and widely used, yet still time-consuming. Especially, in large-scale software systems, developers may forget to change other related functions that must be changed together (aka. co-changes). This may increase the number of review iterations and reviewing time, thus delaying the code review process. Based on our analysis of 66 projects from five open-source systems, we find that there are 16%–33% of code reviews where at least one function must be co-changed, but was not initially changed.

Objectives:

This study aims to propose an approach to recommend co-changed functions in the context of modern code review, which could reduce reviewing time and iterations and help developers identify functions that need to be changed together.

Methods:

We propose CoChangeFinder, a novel method that employs a Graph Neural Network (GNN) to recommend co-changed functions for newly submitted code changes. Then, we conduct a quantitative and qualitative evaluation of CoChangeFinder with 66 studied large-scale open-source software projects.

Results:

Our evaluation results show that our CoChangeFinder outperforms the state-of-the-art approach, achieving 3.44% to 40.45% for top-k accuracy, 2.00% to 26.07% for Recall@k, and 0.04 to 0.21 for mean average precision better than the baseline approach. In addition, our CoChangeFinder demonstrates the capacity to pinpoint the functions related to logic changes.

Conclusion:

Our CoChangeFinder outperforms the baseline approach (i.e., TARMAQ) in recommending co-changed functions during the code review process. Based on our findings, CoChangeFinder could help developers save their time and effort, reduce review iterations, and enhance the efficiency of the code review process.