Test vs Mutant: Adversarial LLM Agents for Robust Unit Test Generation

Fuente: arXiv
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Autores principales: Chang, Pengyu, Fang, Yixiong, Chen, Silin, Shi, Yuling, Shen, Beijun, Gu, Xiaodong
Formato: Preprint
Publicado: 2026
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author Chang, Pengyu
Fang, Yixiong
Chen, Silin
Shi, Yuling
Shen, Beijun
Gu, Xiaodong
author_facet Chang, Pengyu
Fang, Yixiong
Chen, Silin
Shi, Yuling
Shen, Beijun
Gu, Xiaodong
contents Software testing is a critical, yet resource-intensive phase of the software development lifecycle. Over the years, various automated tools have been developed to aid in this process. Search-based approaches typically achieve high coverage but produce tests with low readability, whereas large language model (LLM)-based methods generate more human-readable tests but often suffer from low coverage and compilability. While the majority of research efforts have focused on improving test coverage and readability, little attention has been paid to enhancing the robustness of bug detection, particularly in exposing corner cases and vulnerable execution paths. To address this gap, we propose AdverTest, a novel adversarial framework for LLM-powered test case generation. AdverTest comprises two interacting agents: a test case generation agent (T) and a mutant generation agent (M). These agents engage in an adversarial loop, where M persistently creates new mutants "hacking" the blind spots of T's current test suite, while T iteratively refines its test cases to "kill" the challenging mutants produced by M. This interaction loop is guided by both coverage and mutation scores, enabling the system to co-evolve toward both high test coverage and bug detection capability. Experimental results in the Defects4J dataset show that our approach improves fault detection rates by 8.56% over the best existing LLM-based methods and by 63.30% over EvoSuite, while also improving line and branch coverage.
format Preprint
id arxiv_https___arxiv_org_abs_2602_08146
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Test vs Mutant: Adversarial LLM Agents for Robust Unit Test Generation
Chang, Pengyu
Fang, Yixiong
Chen, Silin
Shi, Yuling
Shen, Beijun
Gu, Xiaodong
Software Engineering
Software testing is a critical, yet resource-intensive phase of the software development lifecycle. Over the years, various automated tools have been developed to aid in this process. Search-based approaches typically achieve high coverage but produce tests with low readability, whereas large language model (LLM)-based methods generate more human-readable tests but often suffer from low coverage and compilability. While the majority of research efforts have focused on improving test coverage and readability, little attention has been paid to enhancing the robustness of bug detection, particularly in exposing corner cases and vulnerable execution paths. To address this gap, we propose AdverTest, a novel adversarial framework for LLM-powered test case generation. AdverTest comprises two interacting agents: a test case generation agent (T) and a mutant generation agent (M). These agents engage in an adversarial loop, where M persistently creates new mutants "hacking" the blind spots of T's current test suite, while T iteratively refines its test cases to "kill" the challenging mutants produced by M. This interaction loop is guided by both coverage and mutation scores, enabling the system to co-evolve toward both high test coverage and bug detection capability. Experimental results in the Defects4J dataset show that our approach improves fault detection rates by 8.56% over the best existing LLM-based methods and by 63.30% over EvoSuite, while also improving line and branch coverage.
title Test vs Mutant: Adversarial LLM Agents for Robust Unit Test Generation
topic Software Engineering
url https://arxiv.org/abs/2602.08146