then:
        1 * a.stop() >> { throw failure1 }
        1 * b.stop() >> { throw failure2 }
        def e = thrown(RuntimeException)
        e == failure1
    }

    def closesACloseableElement() {
        Closeable a = Mock()
        Stoppable b = Mock()

        stoppable.add(a)
        stoppable.add(b)

        when:
        stoppable.stop()

        then:
        1 * a.close()