_ * classDoc.subClasses >> []

        when:
        def result = parse('<root/>')
        withCategories {
            renderer.mergeContent(classDoc, result)
        }

        then:
        formatTree(result) == '''<root>
    <chapter id="classId">
        <title>Class</title>
        <segmentedlist>
            <segtitle>API Documentation</segtitle>
            <seglistitem>
                <seg>

    }

    def formatTree(Closure cl) {
        withCategories {
            return formatTree(cl.call())
        }
    }

    def withCategories(Closure cl) {
        use(BuildableDOMCategory) {
            return cl.call()
        }
    }

    def format(Node... nodes) {
        format(nodes as List)
    }

    def formatTree(Node... nodes) {
        formatTree(nodes as List)