Empirical Comparison of Black-box Test Case Generation Tools for RESTful APIs

TL;DR

This study empirically compares four black-box test case generation tools for RESTful APIs, evaluating their robustness and coverage on real-world services to guide developers in tool selection.

Contribution

It provides the first comprehensive empirical comparison of existing REST API testing tools, highlighting their strengths and weaknesses in practical scenarios.

Findings

RESTler is the most robust, testing all case studies successfully.

RestTestGen achieves the highest test coverage.

Other tools experienced crashes during testing.

Abstract

In literature, we can find research tools to automatically generate test cases for RESTful APIs, addressing the specificity of this particular programming domain. However, no direct comparison of these tools is available to guide developers in deciding which tool best fits their REST API project. In this paper, we present the results of an empirical comparison of automated black-box test case generation approaches for REST APIs. We surveyed the available black-box testing tools that have been proposed in recent literature, finding four usable prototypes: RestTestGen, RESTler, bBOXRT and RESTest. We used these tools to generate test cases for 14 real-world REST services. Then, testing results have been analyzed and compared in terms of robustness (i.e., success rate) and test coverage. Among the considered tools, RESTler appears to be the most solid, able to successfully test all case studies (the other tools experienced crashes). Conversely, test cases generated by RestTestGen scored the highest coverage, suggesting that its testing strategy is the most effective in testing REST APIs.