Missing renderer for Unit Testing within Grails

setup.groovy

controller.metaClass.render = {Map map, Closure closure ->
            renderArgs.putAll(map)

            switch(map.contentType) {
            case null:
                break
            case 'application/xml':
            case 'text/xml':
                def smb = new StreamingMarkupBuilder()
                if (map.encoding){
                    smb.encoding = map.encoding
                }
                delegate.response.outputStream << smb.bind(closure)
                break
            case 'text/json':
                new JSonBuilder(delegate.response).json(closure)
                break
            default:
                println 'Nothing!!'
                break
            }
}