ReCatcher: Towards LLMs Regression Testing for Code Generation

Fuente: arXiv
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Autori principali: Abbassi, Altaf Allah, Da Silva, Leuson, Nikanjam, Amin, Khomh, Foutse
Natura: Preprint
Pubblicazione: 2025
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author Abbassi, Altaf Allah
Da Silva, Leuson
Nikanjam, Amin
Khomh, Foutse
author_facet Abbassi, Altaf Allah
Da Silva, Leuson
Nikanjam, Amin
Khomh, Foutse
contents Large Language Models (LLMs) for code generation evolve rapidly through fine-tuning, merging, or new model releases. However, such updates can introduce regressions, not only in correctness but also in code quality and performance. To address this, we present ReCatcher, a regression testing framework for Python code generation. ReCatcher systematically compares two LLMs, typically a current model and a candidate update, across three dimensions: logical correctness, static code quality, and execution performance. We apply ReCatcher to assess regressions across three update scenarios, fine-tuning, merging, and model release, using CodeLlama, DeepSeek-Coder, and GPT-4o. Our evaluation shows that fine-tuning with cross-language datasets increases syntax errors by up to 12%. Merging with general-purpose models like Llama2 leads to regressions in correctness by up to 18%. GPT-4o introduces regressions of up to 50% in handling missing imports compared to GPT-3.5-turbo, while GPT-4o-mini suffers up to 80% performance degradation in execution time versus GPT-4o. Overall, logical correctness, performance, and error handling (e.g., syntax errors and missing imports) are the most regression-prone areas. Comparing ReCatcher with baseline solutions, it presents better and consistent accuracy across logical and performance aspects. ReCatcher highlights the importance of systematic regression evaluation before adopting new models, while assisting researchers and practitioners in making more informed update decisions.
format Preprint
id arxiv_https___arxiv_org_abs_2507_19390
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle ReCatcher: Towards LLMs Regression Testing for Code Generation
Abbassi, Altaf Allah
Da Silva, Leuson
Nikanjam, Amin
Khomh, Foutse
Software Engineering
Artificial Intelligence
Large Language Models (LLMs) for code generation evolve rapidly through fine-tuning, merging, or new model releases. However, such updates can introduce regressions, not only in correctness but also in code quality and performance. To address this, we present ReCatcher, a regression testing framework for Python code generation. ReCatcher systematically compares two LLMs, typically a current model and a candidate update, across three dimensions: logical correctness, static code quality, and execution performance. We apply ReCatcher to assess regressions across three update scenarios, fine-tuning, merging, and model release, using CodeLlama, DeepSeek-Coder, and GPT-4o. Our evaluation shows that fine-tuning with cross-language datasets increases syntax errors by up to 12%. Merging with general-purpose models like Llama2 leads to regressions in correctness by up to 18%. GPT-4o introduces regressions of up to 50% in handling missing imports compared to GPT-3.5-turbo, while GPT-4o-mini suffers up to 80% performance degradation in execution time versus GPT-4o. Overall, logical correctness, performance, and error handling (e.g., syntax errors and missing imports) are the most regression-prone areas. Comparing ReCatcher with baseline solutions, it presents better and consistent accuracy across logical and performance aspects. ReCatcher highlights the importance of systematic regression evaluation before adopting new models, while assisting researchers and practitioners in making more informed update decisions.
title ReCatcher: Towards LLMs Regression Testing for Code Generation
topic Software Engineering
Artificial Intelligence
url https://arxiv.org/abs/2507.19390