Large Language Models (LLMs), like ChatGPT, have gained widespread popularity and usage in various software engineering tasks, including refactoring, testing, code review, and program comprehension. Despite recent studies delving into refactoring documentation in commit messages, issues, and code review, little is known about how developers articulate their refactoring needs when interacting with ChatGPT. In this paper, our goal is to explore conversations between developers and ChatGPT related to refactoring to better understand how developers identify areas for improvement in code and how ChatGPT addresses developers' needs. Our approach relies on text mining refactoring-related conversations from 17,913 ChatGPT prompts and responses, and investigating developers' explicit refactoring intention. Our results reveal that (1) developer-ChatGPT conversations commonly involve generic and specific terms/phrases; (2) developers often make generic refactoring requests, while ChatGPT typically includes the refactoring intention; and (3) various learning settings when prompting ChatGPT in the context of refactoring. We envision that our findings contribute to a broader understanding of the collaboration between developers and AI models.

Infrastructure-as-Code (IaC) is an emerging software engineering practice that leverages source code to facilitate automated configuration of software systems' infrastructure. IaC files are typically complex, containing hundreds of lines of code and dependencies, making them prone to defects, which can result in breaking online services at scale. To help developers early identify and fix IaC defects, research efforts have introduced IaC defect prediction models at the file level. However, the granularity of the proposed approaches remains coarse-grained, requiring developers to inspect hundreds of lines of code in a file, while only a small fragment of code is defective. To alleviate this issue, we introduce a machine-learning-based approach to predict IaC defects at a fine-grained level, focusing on IaC blocks, i.e., small code units that encapsulate specific behaviours within an IaC file. We trained various machine learning algorithms based on a mixture of code, process, and change-level metrics. We evaluated our approach on 19 open-source projects that use Terraform, a widely used IaC tool. The results indicated that there is no single algorithm that consistently outperforms the others in 19 projects. Overall, among the six algorithms, we observed that the LightGBM model achieved a higher average of 0.21 in terms of MCC and 0.71 in terms of AUC. Models analysis reveals that the developer's experience and the relative number of added lines tend to be the most important features. Additionally, we found that blocks belonging to the most frequent types are more prone to defects. Our defect prediction models have also shown sensitivity to concept drift, indicating that IaC practitioners should regularly retrain their models.

Nowadays, Large Language Models (LLMs) play a pivotal role in software engineering. Developers can use LLMs to address software development-related tasks such as documentation, code refactoring, debugging, and testing. ChatGPT, released by OpenAI, has become the most prominent LLM. In particular, ChatGPT is a cutting-edge tool for providing recommendations and solutions for developers in their pull requests (PRs). However, little is known about the characteristics of PRs that incorporate ChatGPT compared to those without it and what developers usually use it for. To this end, we quantitatively analyzed 243 PRs that listed at least one ChatGPT prompt against a representative sample of 384 PRs without any ChatGPT prompts. Our findings show that developers use ChatGPT in larger, time-consuming pull requests that are five times slower to be closed than PRs that do not use ChatGPT. Furthermore, we perform a qualitative analysis to build a taxonomy of the topics developers primarily address in their prompts. Our analysis results in a taxonomy comprising 8 topics and 32 sub-topics. Our findings highlight that ChatGPT is often used in review-intensive pull requests. Moreover, our taxonomy enriches our understanding of the developer's current applications of ChatGPT.

We aim to explore how developers document their refactoring activities during the software life cycle. We call such activity Self-Affirmed Refactoring (SAR), which indicates developers’ documentation of their refactoring activities. SAR is crucial in understanding various aspects of refactoring, including the motivation, procedure, and consequences of the performed code change. After that, we propose an approach to identify whether a commit describes developer-related refactoring events to classify them according to the refactoring common quality improvement categories. To complement this goal, we aim to reveal insights into how reviewers decide to accept or reject a submitted refactoring request and what makes such a review challenging.Our SAR taxonomy and model can work with refactoring detectors to report any early inconsistency between refactoring types and their documentation. They can serve as a solid background for various empirical investigations. Our survey with code reviewers has revealed several difficulties related to understanding the refactoring intent and implications on the functional and non-functional aspects of the software. In light of our findings from the industrial case study, we recommended a procedure to properly document refactoring activities, as part of our survey feedback.

Modern code review is a widely used technique employed in both industrial and open-source projects to improve software quality, share knowledge, and ensure adherence to coding standards and guidelines. During code review, developers may discuss refactoring activities before merging code changes in the code base. To date, code review has been extensively studied to explore its general challenges, best practices and outcomes, and socio-technical aspects. However, little is known about how refactoring is being reviewed and what developers care about when they review refactored code. Hence, in this work, we present a quantitative and qualitative study to understand what are the main criteria developers rely on to develop a decision about accepting or rejecting a submitted refactored code, and what makes this process challenging. Through a case study of 11,010 refactoring and non-refactoring reviews spread across OpenStack open-source projects, we find that refactoring-related code reviews take significantly longer to be resolved in terms of code review efforts. Moreover, upon performing a thematic analysis on a significant sample of the refactoring code review discussions, we built a comprehensive taxonomy consisting of 28 refactoring review criteria. We envision our findings reaffirming the necessity of developing accurate and efficient tools and techniques that can assist developers in the review process in the presence of refactorings.

Understanding the practice of refactoring documentation is of paramount importance in academia and industry. Issue tracking systems are used by most software projects enabling developers, quality assurance, managers, and users to submit feature requests and other tasks such as bug fixing and code review. Although recent studies explored how to document refactoring in commit messages, little is known about how developers describe their refactoring needs in issues. In this study, we aim at exploring developer-reported refactoring changes in issues to better understand what developers consider to be problematic in their code and how they handle it. Our approach relies on text mining 45,477 refactoring-related issues and identifying refactoring patterns from a diverse corpus of 77 Java projects by investigating issues associated with 15,833 refactoring operations and developers' explicit refactoring intention. Our results show that (1) developers mostly use move refactoring related terms/phrases to target refactoring-related issues; and (2) developers tend to explicitly mention the improvement of specific quality attributes and focus on duplicate code removal. We envision our findings enabling tool builders to support developers with automated documentation of refactoring changes in issues.