when:
        configuration.extendsFrom(configuration2);

        then:
        configuration.extendsFrom == [configuration1, configuration2] as Set

        when:
        def configuration3 = conf("replacedConf")
        configuration.setExtendsFrom([configuration3])

        then:
        configuration.extendsFrom == [configuration3] as Set
    }

    def "extended configurations are not duplicated"() {