Testing and validating REST services in Java is harder than in dynamic languages such as Groovy. REST Assured brings the simplicity of using these languages into the Java domain. It's a great tool for REST API integration tests.

If you are serious about writing an integration test for your REST API, then you must learn the REST Assured and REST API Testing Automation: via REST Assured & HTTP Client course on Udemy is a good place to start with, I have already joined this course and will put some time aside to learn this tool in 2023.

unit testing tool for REST APIs Java

It covers many aspects of REST API testing like Automated REST API Testing using Rest Assured Java and RESTful web service Testing via POSTMAN and HTTP Client.

Read more: https://javarevisited.blogspot.com/2018/01/10-unit-testing-and-integration-tools-for-java-programmers.html#ixzz81f5eEBya