Write and execute a JUnit test for a Java microservice based on MicroProfile and run both in the OpenLiberty development mode

This blog post has the focus on: how to develop a JUnit test for the Authors microservice from the Cloud Native Starter example and run both the Authors microservice and the JUnit test on OpenLiberty in the development mode.

That blog post hasn’t the objective to be a blueprint or a ‘how to guide’ for writing JUnit tests,  JUnit test organization, test strategy and so on. The objective is to get technically started along one concrete microservice example from the Cloud Native Starter project.

The Authors microservice has one RESTful api endpoint called getAuthor. The endpoint provides one parameter for the Author name. The endpoint returns Author data in a JSON format.

Keep the end in mind: The gif shows a sample JUnit test execution for the Author microservice using OpenLiberty in the Visual Studio Code editor:

junit-on-openliberty-run-test

Note: As an alternative or in addition, you can also visit the OpenLiberty tutorial “MicroProfile or Jakarta EE application” to start with that topic.

Let’s start with: What do we need and how do we realize the implementation?

We need to ..

    •  invoke the REST endpoint of the Authors microservice with a REST Client.
    •  transform the JSON response of the REST endpoint to an Author data class
    •  handle different values to invoke the REST Endpoint parameter for the Author name to run tests with variations of the Author name.
    • compare the actual response value with an expected value and document the result.

Continue reading