# Restats: A Test Coverage Tool for RESTful APIs

arXiv: https://arxiv.org/abs/2108.08209 · HTML: https://mlsanity.com/paper/2108.08209/

## Key facts

- Cited by 4 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 18 Aug 2021.

## Built on by (most cited first, 4 of 4)

- [From REST to MCP: An Empirical Study of API Wrapping and Automated Server Generation for LLM Agents](https://mlsanity.com/paper/2507.16044/) (2025)
- [FuzzTheREST: An Intelligent Automated Black-box RESTful API Fuzzer](https://mlsanity.com/paper/2407.14361/) (2024)
- [Test Amplification for REST APIs via Single and Multi-Agent LLM Systems](https://mlsanity.com/paper/2504.08113/) (2025)
- [Agentic LLMs for REST API Test Amplification: A Comparative Study Across Cloud Applications](https://mlsanity.com/paper/2510.27417/) (2025)

## Abstract (arXiv)

Test coverage is a standard measure used to evaluate the completeness of a test suite. Coverage is typically computed on source code, by assessing the extent of source code entities (e.g., statements, data dependencies, control dependencies) that are exercised when running test cases. When considering REST APIs, an alternative perspective to assess test suite completeness is with respect to the service definition. This paper presents Restats, a test coverage tool for REST APIs that supports eight state-of-the-art test coverage metrics with a black-box perspective, i.e., only relying on the OpenAPI interface specification of the REST API under test. In fact, metrics are computed by only observing the HTTP requests and responses occurring at testing time, and no access to source/compiled code of the REST API is required. These coverage metrics come in handy for: (i) developers and test engineers working at development and maintenance tasks; (ii) stakeholders and customers who want to evaluate the completeness of acceptance tests; (iii) researches interested in comparing different automated test case generation strategies.