- Research Article
- 10.1145/3771555
VUI Testing of VPA Apps via Behavior Model-Enhanced LLM Agents
- Oct 10, 2025
- ACM Transactions on Software Engineering and Methodology
- Suwan Li + 6 more +6
With the increasing adoption of smart speakers, Virtual Personal Assistant (VPA) applications have become integral to daily life, enabling users to access news, entertainment, and smart device control through Voice User Interfaces (VUI). However, many VPA apps suffer from quality issues, such as unexpected terminations and failures to process common user commands, highlighting the urgent need for systematic and efficient VUI testing. Existing chatbot-style and model-based testing approaches lack global and semantic awareness, resulting in ineffective test case generation and inefficient state exploration. To address these challenges, we introduce Elevate, a model-enhanced, LLM-driven VPA testing framework that employs a multi-agent architecture to enhance VUI behavior testing. Elevate comprises three specialized LLM agents—Observer, Generator, and Planner—that collaboratively perform state extraction, test case generation, and guided state exploration. Additionally, a deterministic finite automaton (DFA)-based behavior model is designed to abstract app behavior and provide structured guidance to LLM agents, enhancing testing performance. Elevate also incorporates a feedback mechanism that refines testing strategies based on observed behaviors, ensuring continuous improvement. Implemented using GPT-4-Turbo and DeepSeek-R1, Elevate has been evaluated on problem detection, sentence/semantic coverage, and large-scale testing. Experimental results show that Elevate outperforms state-of-the-art methods (Vitas and LLM-based chatbots), detecting at least 18 and 37 more problems, respectively, and achieving over 10% and 30% higher state coverage. In a large-scale evaluation on 4,000 Alexa skills, Elevate further demonstrated 15% higher coverage than Vitas, confirming its effectiveness, scalability, and potential for widespread application in VUI testing.
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