COTS: Connected OpenAPI Test Synthesis for RESTful Applications

TL;DR

This paper introduces COTS, a model-driven testing approach for RESTful APIs using a new domain-specific language inspired by session types, which effectively detects subtle defects and achieves high coverage.

Contribution

The paper presents a novel DSL for OpenAPI and a supporting tool that generates randomized, model-based tests to improve REST API testing effectiveness.

Findings

Identifies nuanced defects in REST APIs

Achieves comparable or better coverage than larger test suites

Effective on multiple open source applications

Abstract

We present a novel model-driven approach for testing RESTful applications. We introduce a (i) domain-specific language for OpenAPI specifications and (ii) a tool to support our methodology. Our DSL is inspired by session types and enables the modelling of communication protocols between a REST client and server. Our tool, dubbed COTS, generates (randomised) model-based test executions and reports software defects. We evaluate the effectiveness of our approach by applying it to test several open source applications. Our findings indicate that our methodology can identify nuanced defects in REST APIs and achieve comparable or superior code coverage when compared to much larger handcrafted test suites.