Give JUnit 4 precedence over JUnit Platform and TestNG For backwards compatibility, JUnit 4 takes precendence over TestNG and JUnit Platform since groovy-all ships with dependencies on both. In the latter case, JUnit Platform is used if both junit-vintage-engine and JUnit 4 are on the classpath.
Autodetect TestFramework if none is configure explicitly When the TestFramework of a Test task is not configured explicitly it used to default to `useJUnit()`. Now, the task's classpath is inspected for a junit-platform-engine.jar or testng.jar. If one of them is found, the task uses the JUnit Platform or TestNG to execute tests, respectively.
Since we have internal dependencies on the JUnit Platform and TestNG, all Test tasks in our own build are configured to `useJUnit()` and explicitly.