final SourceSet testSourceSet = sourceSets.create("test");

        project.getTasks().withType(Test.class).configureEach(test -> {
            test.setTestClassesDirs(testSourceSet.getOutput().getClassesDirs());
            test.setClasspath(testSourceSet.getRuntimeClasspath());
        });

        // create a compileOnly configuration as others might expect it

            project.getPlugins().withType(JavaPlugin.class, t ->
                testTask.mustRunAfter(project.getTasks().named("test"))
            );

            testTask.setTestClassesDirs(sourceSet.getOutput().getClassesDirs());
            testTask.setClasspath(sourceSet.getRuntimeClasspath());