|| sourceSet.getName().equals(SourceSet.TEST_SOURCE_SET_NAME)
            )
            .map(sourceSet -> sourceSet.getOutput().getClassesDirs())
            .reduce(FileCollection::plus)
            .orElse(getProject().files())
            .filter(File::exists);
    }

        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.getConfigurations().create("compileOnly");

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

            testTask.setTestClassesDirs(sourceSet.getOutput().getClassesDirs());
            testTask.setClasspath(sourceSet.getRuntimeClasspath());
            // if this a module or plugin, it may have an associated zip file with it's contents, add that to the test cluster