JUnit 6 is here, what does it mean for Vert.x users?

The JUnit team has officially released JUnit 6, marking a significant milestone in the evolution of one of the most widely used testing frameworks in the Java ecosystem. This new version brings a lot of improvements aimed at modernizing the testing experience, streamlining configuration, and enhancing extensibility. Here’s a quick look at the highlights, and what they mean for Vert.x developers.

JUnit 6 highlights

JUnit 6 builds on the solid foundation of JUnit 5, introducing several key enhancements:

Unified extension model: A more consistent and powerful way to extend JUnit’s behavior.
Improved test discovery: Faster and more flexible test discovery mechanisms.
Better IDE and build tool integration: Enhanced support for modern build tools and IDEs.
Native support for Java 17+: JUnit 6 requires Java 17 or newer, aligning with the latest LTS releases and encouraging adoption of modern Java features.

`vertx-junit5` compatibility

Good news for Vert.x 5 users: the vertx-junit5 module is fully compatible with JUnit 6. This means you can continue writing reactive tests using @VertxExtension, VertxTestContext and other utilities without any changes to your test code.

However, there are a couple of important considerations to keep in mind when upgrading.

Java 17 is now required

Since JUnit 6 mandates Java 17 as the minimum supported version, your Vert.x project must be built with and run on a Java 17+ JVM. If you’re still on Java 11 or earlier, you must stick to JUnit 5.

Maven BOM configuration

JUnit 6 introduces a new BOM (Bill of Materials) for dependency management. To ensure that your project uses the correct versions of JUnit 6 artifacts, and avoids falling back to JUnit 5 via transitive dependencies, you must explicitly import the JUnit BOM in your pom.xml:

<dependencyManagement>
  <dependency>
    <groupId>io.vertx</groupId>
    <artifactId>vertx-stack-depchain</artifactId>
    <version>5.0.4</version>
    <type>pom</type>
    <scope>import</scope>
  </dependency>
  <dependency>
    <groupId>org.junit</groupId>
    <artifactId>junit-bom</artifactId>
    <version>6.0.0</version>
    <type>pom</type>
    <scope>import</scope>
  </dependency>
</dependencyManagement>
 
<dependencies>
  <dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter</artifactId>
    <scope>test</scope>
  </dependency>
  <dependency>
    <groupId>io.vertx</groupId>
    <artifactId>vertx-junit5</artifactId>
    <scope>test</scope>
  </dependency>
</dependencies>

The release of JUnit 6 is a welcome update for Java developers, and we’re excited that vertx-junit5 is ready to support it. Just remember to upgrade your JVM to Java 17 and configure your Maven project correctly to avoid dependency conflicts.

We encourage you to try it out with vertx-junit5. If you run into issues, have suggestions, or just want to share your experience, we’d love to hear from you! Join the conversation on GitHub, or reach out on the Vert.x community channels.

Happy testing!