Test driven development gets interesting when actions might or might not complete somewhen in the future. Point in case: HTTP requests (fetch returns a promise)

vert.x and jUnit5

I frequently write little tests, that spin up an http sever before the test, run individual tests using a WebClient. All these operations run asynchronous, returning a vert.x Future (In JavaScript Land the equivalent would be a promise)

To make this pain free, vert.x provides a full integration into jUnit 5. Using the annotation @ExtendWith(VertxExtension.class) vert.x provides two injectable parameters: Vertx and VertxTestContext. Add the simple mental rule: All async operations need to interact with the VertxTestContext.