如何在golang中为我的测试用例正确创建模拟http.request？

I want to write a test case to verify my parameter parser function. The following is my sample code to mock a http.request

rawUrl := "http://localhost/search/content?query=test"

func createSearchRequest(rawUrl string) SearchRequest {
    api := NewWebService()

    req, err := http.NewRequest("POST", rawUrl, nil)
    if err != nil {
        logger.Fatal(err)
    }
    logger.Infof("%v", req)
    return api.searchRequest(req)
}

My web server use github.com/gorilla/mux as route

router := mux.NewRouter()

router.HandleFunc("/search/{query_type}", searchApiService.Search).Methods("GET")

{query_type}http.request

func (api WebService) searchRequest(req *http.Request){
    // skip ....

    vars := mux.Vars(req)
    queryType := vars["query_type"]
    logger.Infof("queryType:%v", queryType)

    //skip ....
}

How can I get mux's path parameter in my test case?