Can't access mux params when testing API endpoint with custom handlers - api

Question

I have a custom handler for my API endpoints like this:
type HTTPError struct {
Error error
Message string
Code int
}
type endpointREST func(http.ResponseWriter, *http.Request) *HTTPError
func (fn endpointREST) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if e := fn(w, r); e != nil {
http.Error(w, e.Message, e.Code)
}
}
my example route look like this:
func GetShare(w http.ResponseWriter, r *http.Request) *HTTPError {
vars := mux.Vars(r)
fmt.Println(r.URL) // http://127.0.0.1:36455/share/5713d228-a042-446d-a5e4-183b19fa832a
fmt.Println(vars) // -->> always empty map when testing
return nil
}
These routes work well (manual, using Postman) after setting them up with
router := mux.NewRouter().StrictSlash(true)
handler := cors.Default().Handler(router)
router.Handle("/share/{id}", endpointREST(GetShare)).Methods("GET")
log.Fatal(http.ListenAndServe(":6969", handler))
The Problem is, that i can't test the API this way, since mux.Vars(r) will always return an empty map in the testing environment.
This is my testing code:
func TestGetShare(t *testing.T) {
Reset()
router := mux.NewRouter()
ts := httptest.NewServer(router)
router.Handle("/share/{id}", endpointREST(GetShare)).Methods("GET")
defer ts.Close()
t.Run("unauthorized", func(t *testing.T) {
req, _ := http.NewRequest("GET", ts.URL + "/share/5713d228-a042-446d-a5e4-183b19fa832a", nil)
res, _ := http.DefaultClient.Do(req)
assert.Equal(t, http.StatusUnauthorized, res.StatusCode)
})
}

Answer 1

I suggest you tu use the SetURLVars test helper func:
// SetURLVars sets the URL variables for the given request, to be accessed via
// mux.Vars for testing route behaviour. Arguments are not modified, a shallow
// copy is returned.
//
// This API should only be used for testing purposes; it provides a way to
// inject variables into the request context. Alternatively, URL variables
// can be set by making a route that captures the required variables,
// starting a server and sending the request to that server.
func SetURLVars(r *http.Request, val map[string]string) *http.Request {
return requestWithVars(r, val)
}