conf1.extendsFrom(conf2)
        conf2.extendsFrom(configuration)

        then:
        thrown InvalidUserDataException
    }

    def "reports cycle introduced by setExtends"() {
        def configuration = conf()
        def otherConf = conf("other")
        configuration.extendsFrom(otherConf)

        when:
        otherConf.setExtendsFrom([configuration])

        then:

            Set<String> configsToAdd = new HashSet<>();
            Configuration[] configs = md.getConfigurations();
            for (Configuration config : configs) {
                String[] ext = config.getExtends();
                for (String s : ext) {
                    if (conf.equals(s)) {
                        String configName = config.getName();
                        configsToAdd.add(configName);