RESTifAI: LLM-Based Workflow for Reusable REST API Testing

TL;DR

RESTifAI is an LLM-based tool that generates reusable REST API tests, covering both successful and failure scenarios, and is suitable for CI/CD pipelines, addressing limitations of existing tools.

Contribution

Introduces RESTifAI, a novel LLM-driven approach for systematic, reusable REST API testing that covers happy paths and negative cases, improving over existing tools.

Findings

Performs comparably to state-of-the-art LLM tools

Addresses reusability and oracle complexity issues

Demonstrated in industrial service scenarios

Abstract

With this paper, we introduce RESTifAI, an LLM-driven approach for generating reusable, CI/CD ready REST API tests, following the happy-path approach. Unlike existing tools that often focus primarily on internal server errors, RESTifAI systematically constructs valid test scenarios (happy paths) and derives negative cases to verify both intended functionality (2xx responses) and robustness against invalid inputs or business-rule violations (4xx responses). The results indicate that RESTifAI performs on par with the latest LLM tools, i.e., AutoRestTest and LogiAgent, while addressing limitations related to reusability, oracle complexity, and integration. To support this, we provide common comparative results and demonstrate the tool's applicability in industrial services. For tool demonstration, please refer to https://www.youtube.com/watch?v=2vtQo0T0Lo4. RESTifAI is publicly available at https://github.com/casablancahotelsoftware/RESTifAI.