Various Approaches of Spring Controller Testing

(forked and converted to kotlin)

This small repository provides some example Spring Boot Tests verifying the correct implementation of a very simple RestController. (If you are new to this topic, you can start with this "Building a RESTful Web Service" tutorial.)

The tests can be done with a manually wired MockMvc client or with a with a manually wired WebTestClient client.

If the class creation is under the control of Spring, the MockMvc client will by automatically wired and then can be run against a mocked servlet or an embedded server. Similar, WebTestClient client will by automatically wired and then can be run against a mocked servlet or an embedded server. (Both approaches are described here (mock environment) and here (running server).)

However, the straight-forward solution to test by MockMvc is to run a WebMvcTest. Correspondingly, the straight-forward solution to test by WebTestClient is to run a WebFluxTest.

In order to see all the tests succeeding, just check out and run mvn test.

• Note #1: Thanks to JUnit5's Extension Model, the RunWith annotation is not required anymore.
• Note #2: Since JUnit5 supports n-ary test methods, the Autowired clients might be provided as a test method parameter or (not shown in the code) might be declared as test class fields. (Also annotated with Autowired.)
• Note #3: This simple Maven project specifies a MVC controller but additionally uses WebFlux for testing. Spring explicitly allows both modules to be used simultaneously – but one is preferred over the other. Thus, if the WebTestClient requires a WebFlux Context, the spring.main.web-application-type must be specified accordingly.