Hi Marc, Thanks for the links to the documentation. This really helps for my Arquillian-Spock extension. It's good to know the LauncherSession was introduced to solve this issue.
The problem I see with this new API is that it requires the extension to explicitly make use of it. For example, the JUnit 5 Arquillian extension will need to be adapted to this new API to work correctly with a forkCount > 1. The same will probably hold for other extensions. The cause of this is that separate invocations of the launcher do not really share a life cycle. LauncherSession is able to bind these invocations together, but the engine will be run over and over again. JUnit does support streaming tests in a lazy way via the DynamicTest API. It would be great if this could somehow be exposed via the LauncherDiscoveryRequest. That would IMHO really solve this issue. Best regards, Emond On Sat, Sep 11, 2021 at 7:52 AM Marc Philipp <m...@gradle.com> wrote: > Hi Emond and Tibor, > > I’m glad you discovered the new LauncherSession API which was added for > this purpose. The JUnit 5.8 GA release will come in the next few days. > > As you mentrioned, the official documentation does not (yet!) do a good > job of explaining its intended use case: > > https://junit.org/junit5/docs/5.8.0-RC1/user-guide/#launcher-api-launcher-session-listeners-custom > > Here’s a more complete example that I wrote for Gradle’s test distribution > plugin: > > https://docs.gradle.com/enterprise/test-distribution-gradle-plugin/#junit_5_8_and_later > > It demonstrates how to initialize a “fixture” only once for an entire > session and only if tests are actually going to be executed not just > discovered. I’ll make sure to update the official JUnit docs to include a > similar example before the release. > > To only differentiate between the different versions of JUnit in one place > and stay backwards compatible, you could create an adapter class like this: > > public class BackwardsCompatibleLauncherSession implements AutoCloseable { > > public static BackwardsCompatibleLauncherSession open() { > try { > LauncherSession launcherSession = > LauncherFactory.openSession(); > return new > BackwardsCompatibleLauncherSession(launcherSession.getLauncher(), > launcherSession::close); > } catch (NoSuchMethodError ignore) { > // JUnit Platform version on test classpath does not yet > support launcher sessions > return new > BackwardsCompatibleLauncherSession(LauncherFactory.create(), () -> {}); > } > } > > private final Launcher launcher; > private final Runnable onClose; > > private BackwardsCompatibleLauncherSession(Launcher launcher, Runnable > onClose) { > this.launcher = launcher; > this.onClose = onClose; > } > > Launcher getLauncher() { > return launcher; > } > > @Override > public void close() { > onClose.run(); > } > } > > Cheers, > > Marc >
