使用自定义ServeHTTP实现的HTTP处理程序的golang单元测试

Question

I am trying to write unit test for my http file server. I have implemented the ServeHTTP function so that it'd replace "//" with "/" in the URL:

type slashFix struct {
    mux http.Handler
}

func (h *slashFix) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    r.URL.Path = strings.Replace(r.URL.Path, "//", "/", -1)
    h.mux.ServeHTTP(w, r)
}

The bare-minimum code would look like this:

func StartFileServer() {
    httpMux := http.NewServeMux()
    httpMux.HandleFunc("/abc/", basicAuth(handle))
    http.ListenAndServe(":8000", &slashFix{httpMux})
}

func handle(writer http.ResponseWriter, r *http.Request) {
    dirName := "C:\\Users\\gayr\\GolandProjects\\src\\NDAC\\download\\"    
    http.StripPrefix("/abc",
        http.FileServer(http.Dir(dirName))).ServeHTTP(writer, r)
}

func basicAuth(handler http.HandlerFunc) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        user, pass, ok := r.BasicAuth()
        if user != "UserName" || pass != "Password" {
            w.WriteHeader(401)
            w.Write([]byte("Unauthorised.
"))
            return
        }
        handler(w, r)
    }
}

I came across instances like the following to test http handlers:

req, err := http.NewRequest("GET", "/abc/testfile.txt", nil)
if err != nil {
    t.Fatal(err)
}
req.SetBasicAuth("UserName", "Password")
rr := httptest.NewRecorder()
handler := http.HandlerFunc(basicAuth(handle))
handler.ServeHTTP(rr, req)

Doing so would invoke the ServeHTTP function implemented using http.HandleFunc, but I want ServeHTTP implemented in my code to be invoked. How can this be achieved? Also, is there a way for me to directly test StartFileServer()?

Edit: I checked the link provided in the comments; my question does not appear to be a duplicate. I have a specific question: instead of invoking the ServeHTTP function implemented using http.HandleFunc, I want ServeHTTP implemented in my code to be invoked. I do not see this addressed in the provided link.

Answer 1

http.HandlerFunc implements http.Handler. As Flimzy pointed out in the comments, there is no need for basicAuth to require a HandlerFunc; any http.Handler will do. Sticking to the http.Handler interface instead of the concrete HandlerFunc type will make everything easily composable:

func basicAuth(handler http.Handler) http.Handler { // Note: http.Handler, not http.HandlerFunc
        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
                user, pass, ok := r.BasicAuth()
                if !ok {
                        // TODO
                }
                if user != "UserName" || pass != "Password" {
                        w.WriteHeader(401)
                        w.Write([]byte("Unauthorised.
"))
                        return
                }

                handler.ServeHTTP(w, r)
        })
}

func TestFoo(t *testing.T) {
        req, err := http.NewRequest("GET", "/abc/testfile.txt", nil)
        if err != nil {
                t.Fatal(err)
        }
        req.SetBasicAuth("UserName", "Password")
        rr := httptest.NewRecorder()

        // composition is trivial now
        sf := &slashFix{
                mux: http.HandlerFunc(handle),
        }
        handler := basicAuth(sf)
        handler.ServeHTTP(rr, req)

        // assert correct rr
}