TestAgent: A Multi-Agent LLM Framework for Repository-Level Unit Test Generation
Automated unit test generation plays a critical role in maintaining software quality, yet existing LLM-based tools often struggle with limited repository-level context and rigid generation workflows. In this paper, we present TestAgent, a multi-agent tool implemented as a VS Code extension that automates the generation of high-quality unit tests for Java projects using repository-level Code Knowledge Graphs. Unlike existing tools that rely on coarse-grained workflows, TestAgent mirrors the structured practices of human developers, who typically analyze requirements before writing tests and review results afterward, by coordinating three specialized agents: a Planner to derive testing requirements, a Generator to synthesize executable code via tool-assisted retrieval, and a Reviewer to iteratively refine tests based on execution feedback. Evaluation on 1,451 methods across six Java projects demonstrates that TestAgent achieves a 92.34% line coverage, significantly outperforming baselines like EvoSuite and ChatUniTest. Furthermore, the tool successfully detects 154 real-world bugs with high precision (92.22%), demonstrating its practical utility for regression testing and bug discovery. The tool source code and demonstration are available at: https://github.com/iSEngLab/TestAgent-VSCode-Extension.