Improved testing support

On the testing front, the Spring Framework 5.0 likewise accompanies JUnit Jupiter (https://junit.org/junit5/docs/current/user-guide/). It helps in writing tests and extensions in JUnit 5. It also gives a test engine to run Jupiter-constructed tests with respect to Spring and also provides a programming and extension model.

The Spring Framework 5.0 additionally underpins parallel test execution in the Spring TestContext Framework. For Spring WebFlux, spring-test likewise incorporates bolster for WebTestClient to integrate testing support for the reactive programming model.

There is no compelling reason to run a server for testing scenarios. By utilizing a new WebTestClient, which is like MockMvc, WebTestClient can bind specifically to the WebFlux server infrastructure using a mock request and response.