Rename WriteErrorResponse() to simply ErrorJSON() and reorder arguments

This way we better mimic net/http.Error()

https://pkg.go.dev/net/http?tab=doc#Error

internal/server/control/control.go

@@ -53,7 +53,7 @@ func removeRoute(res http.ResponseWriter, req *http.Request) {
 	vars := mux.Vars(req)
 	id := vars["id"]
 	if err := funcRemove(id); err != nil {
-		srverrors.WriteErrorResponse(http.StatusNotFound, "Route Not Found", res)
+		srverrors.ErrorJSON(res, "Route Not Found", http.StatusNotFound)
 		return
 	}
 
@@ -94,29 +94,29 @@ func addRoute(res http.ResponseWriter, req *http.Request) {
 	payload, _ := ioutil.ReadAll(req.Body)
 	err := json.Unmarshal(payload, &route)
 	if err != nil {
-		srverrors.WriteErrorResponse(http.StatusBadRequest, "Malformed JSON", res)
+		srverrors.ErrorJSON(res, "Malformed JSON", http.StatusBadRequest)
 		return
 	}
 
 	if route.Method == "" {
-		srverrors.WriteErrorResponse(http.StatusUnprocessableEntity, "Invalid Route", res)
+		srverrors.ErrorJSON(res, "Invalid Route", http.StatusUnprocessableEntity)
 		return
 	}
 
 	if route.Pattern == "" {
-		srverrors.WriteErrorResponse(http.StatusUnprocessableEntity, "Invalid Route", res)
+		srverrors.ErrorJSON(res, "Invalid Route", http.StatusUnprocessableEntity)
 		return
 	}
 
 	err = pathValidator(route.Pattern)
 	if err != nil {
-		srverrors.WriteErrorResponse(http.StatusUnprocessableEntity, "Invalid Route", res)
+		srverrors.ErrorJSON(res, "Invalid Route", http.StatusUnprocessableEntity)
 		return
 	}
 
 	id, err := idGenerator()
 	if err != nil {
-		srverrors.WriteErrorResponse(http.StatusInternalServerError, "Internal Server Error", res)
+		srverrors.ErrorJSON(res, "Internal Server Error", http.StatusInternalServerError)
 		return
 	}
 
@@ -138,7 +138,7 @@ var funcGet func(string) (model.Route, error) = user.Routes.Get
 func getRoute(res http.ResponseWriter, req *http.Request) {
 	id := mux.Vars(req)["id"]
 	if r, err := funcGet(id); err != nil {
-		srverrors.WriteErrorResponse(http.StatusNotFound, "Route Not Found", res)
+		srverrors.ErrorJSON(res, "Route Not Found", http.StatusNotFound)
 	} else {
 		res.Header().Set("Content-Type", "application/json")
 		rBytes, _ := json.Marshal(r)

internal/server/data/decorator.go

@@ -40,7 +40,7 @@ func checkHandler(fn resourceHandler) func(http.ResponseWriter, *http.Request) {
 		if h, ok := Handlers.Get(handlerID); ok {
 			fn(w, r, h)
 		} else {
-			srverrors.WriteErrorResponse(http.StatusNotFound, "Handler ID Not Found", w)
+			srverrors.ErrorJSON(w, "Handler ID Not Found", http.StatusNotFound)
 		}
 	}
 }

internal/server/data/resource.go

@@ -40,7 +40,7 @@ func getRequestBody(w http.ResponseWriter, r *http.Request, h *model.Handler) {
 	n, err := io.Copy(w, h.Request.Body)
 	if err != nil {
 		if n == 0 {
-			srverrors.WriteErrorResponse(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError), w)
+			srverrors.ErrorJSON(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 		} else {
 			// Only way to abort current connection as of go 1.13
 			// https://github.com/golang/go/issues/16542
@@ -72,7 +72,7 @@ func getRequestMatches(w http.ResponseWriter, r *http.Request, h *model.Handler)
 	if value, ok := vars[name]; ok {
 		_, _ = w.Write([]byte(value))
 	} else {
-		srverrors.WriteErrorResponse(http.StatusNotFound, ResourceItemNotFound, w)
+		srverrors.ErrorJSON(w, ResourceItemNotFound, http.StatusNotFound)
 	}
 }
 
@@ -82,7 +82,7 @@ func getRequestParams(w http.ResponseWriter, r *http.Request, h *model.Handler)
 	if values, ok := h.Request.URL.Query()[name]; ok {
 		_, _ = w.Write([]byte(values[0]))
 	} else {
-		srverrors.WriteErrorResponse(http.StatusNotFound, ResourceItemNotFound, w)
+		srverrors.ErrorJSON(w, ResourceItemNotFound, http.StatusNotFound)
 	}
 }
 
@@ -92,7 +92,7 @@ func getRequestHeaders(w http.ResponseWriter, r *http.Request, h *model.Handler)
 	if values, ok := h.Request.Header[textproto.CanonicalMIMEHeaderKey(name)]; ok {
 		_, _ = w.Write([]byte(values[0]))
 	} else {
-		srverrors.WriteErrorResponse(http.StatusNotFound, ResourceItemNotFound, w)
+		srverrors.ErrorJSON(w, ResourceItemNotFound, http.StatusNotFound)
 	}
 }
 
@@ -102,7 +102,7 @@ func getRequestCookies(w http.ResponseWriter, r *http.Request, h *model.Handler)
 	if cookie, err := h.Request.Cookie(name); err == nil {
 		_, _ = w.Write([]byte(cookie.Value))
 	} else {
-		srverrors.WriteErrorResponse(http.StatusNotFound, ResourceItemNotFound, w)
+		srverrors.ErrorJSON(w, ResourceItemNotFound, http.StatusNotFound)
 	}
 }
 
@@ -118,11 +118,11 @@ func getRequestForm(w http.ResponseWriter, r *http.Request, h *model.Handler) {
 	// We tried to exercise this execution path but didn't know how.
 	err := h.Request.ParseForm()
 	if err != nil {
-		srverrors.WriteErrorResponse(http.StatusNotFound, ResourceItemNotFound, w)
+		srverrors.ErrorJSON(w, ResourceItemNotFound, http.StatusNotFound)
 	} else if values, ok := h.Request.Form[name]; ok {
 		_, _ = w.Write([]byte(values[0]))
 	} else {
-		srverrors.WriteErrorResponse(http.StatusNotFound, ResourceItemNotFound, w)
+		srverrors.ErrorJSON(w, ResourceItemNotFound, http.StatusNotFound)
 	}
 }
 
@@ -133,7 +133,7 @@ func getRequestFileName(w http.ResponseWriter, r *http.Request, h *model.Handler
 	if err == nil {
 		_, _ = w.Write([]byte(header.Filename))
 	} else {
-		srverrors.WriteErrorResponse(http.StatusNotFound, ResourceItemNotFound, w)
+		srverrors.ErrorJSON(w, ResourceItemNotFound, http.StatusNotFound)
 	}
 }
 
@@ -144,7 +144,7 @@ func getRequestFileContent(w http.ResponseWriter, r *http.Request, h *model.Hand
 	if err == nil {
 		_, _ = io.Copy(w, file)
 	} else {
-		srverrors.WriteErrorResponse(http.StatusNotFound, ResourceItemNotFound, w)
+		srverrors.ErrorJSON(w, ResourceItemNotFound, http.StatusNotFound)
 	}
 }
 
@@ -153,14 +153,14 @@ func getRequestFileContent(w http.ResponseWriter, r *http.Request, h *model.Hand
 func setResponseStatus(w http.ResponseWriter, r *http.Request, h *model.Handler) {
 	sb, err := ioutil.ReadAll(r.Body)
 	if err != nil {
-		srverrors.WriteErrorResponse(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError), w)
+		srverrors.ErrorJSON(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 		return
 	}
 
 	if si, err := strconv.Atoi(string(sb)); err != nil {
-		srverrors.WriteErrorResponse(http.StatusUnprocessableEntity, NonIntegerValue, w)
+		srverrors.ErrorJSON(w, NonIntegerValue, http.StatusUnprocessableEntity)
 	} else if http.StatusText(si) == "" {
-		srverrors.WriteErrorResponse(http.StatusBadRequest, InvalidStatusCode, w)
+		srverrors.ErrorJSON(w, InvalidStatusCode, http.StatusBadRequest)
 	} else {
 		h.Writer.WriteHeader(int(si))
 	}
@@ -170,7 +170,7 @@ func setResponseHeaders(w http.ResponseWriter, r *http.Request, h *model.Handler
 	name := mux.Vars(r)["name"]
 	vb, err := ioutil.ReadAll(r.Body)
 	if err != nil {
-		srverrors.WriteErrorResponse(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError), w)
+		srverrors.ErrorJSON(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 		return
 	}
 
@@ -186,7 +186,7 @@ func setResponseCookies(w http.ResponseWriter, r *http.Request, h *model.Handler
 	name := mux.Vars(r)["name"]
 	vb, err := ioutil.ReadAll(r.Body)
 	if err != nil {
-		srverrors.WriteErrorResponse(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError), w)
+		srverrors.ErrorJSON(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 		return
 	}
 
@@ -199,6 +199,6 @@ func setResponseBody(w http.ResponseWriter, r *http.Request, h *model.Handler) {
 		if n > 0 {
 			panic("Truncated body")
 		}
-		srverrors.WriteErrorResponse(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError), w)
+		srverrors.ErrorJSON(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 	}
 }

internal/server/data/server.go

@@ -38,7 +38,7 @@ func configRouter(rs []routeSpec) (r *mux.Router) {
 	r.HandleFunc(
 		"/handlers/{handlerID}/{resource:.*}",
 		func(w http.ResponseWriter, r *http.Request) {
-			srverrors.WriteErrorResponse(http.StatusBadRequest, "Invalid Resource Path", w)
+			srverrors.ErrorJSON(w, "Invalid Resource Path", http.StatusBadRequest)
 		})
 	return r
 }

internal/server/srverrors/error.go

@@ -10,13 +10,15 @@ type ServerErrMessage struct {
 	Reason string `json:"reason"`
 }
 
-// WriteErrorResponse writes the error JSON body to the provided http.ResponseWriter,
-// after setting the appropiate Content-Type header
-func WriteErrorResponse(statusCode int, reasonMsg string, res http.ResponseWriter) {
-	respBody := ServerErrMessage{}
-	respBody.Reason = reasonMsg
-	bb, _ := json.Marshal(respBody)
-	res.Header().Set("Content-Type", "application/json; charset=utf-8")
-	res.WriteHeader(statusCode)
-	_, _ = res.Write(bb)
+// ErrorJSON writes the provided error as a JSON body to the provided
+// http.ResponseWriter, after setting the appropriate Content-Type header
+func ErrorJSON(w http.ResponseWriter, error string, code int) {
+	body, _ := json.Marshal(
+		ServerErrMessage{
+			Reason: error,
+		},
+	)
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.WriteHeader(code)
+	_, _ = w.Write(body)
 }

internal/server/srverrors/error_test.go

@@ -10,31 +10,31 @@ import (
 	"github.com/BBVA/kapow/internal/server/srverrors"
 )
 
-func TestWriteErrorResponseSetsAppJsonContentType(t *testing.T) {
+func TestErrorJSONSetsAppJsonContentType(t *testing.T) {
 	w := httptest.NewRecorder()
 
-	srverrors.WriteErrorResponse(0, "Not Important Here", w)
+	srverrors.ErrorJSON(w, "Not Important Here", 0)
 
 	if v := w.Result().Header.Get("Content-Type"); v != "application/json; charset=utf-8" {
 		t.Errorf("Content-Type header mismatch. Expected: %q, got: %q", "application/json; charset=utf-8", v)
 	}
 }
 
-func TestWriteErrorResponseSetsRequestedStatusCode(t *testing.T) {
+func TestErrorJSONSetsRequestedStatusCode(t *testing.T) {
 	w := httptest.NewRecorder()
 
-	srverrors.WriteErrorResponse(http.StatusGone, "Not Important Here", w)
+	srverrors.ErrorJSON(w, "Not Important Here", http.StatusGone)
 
 	if v := w.Result().StatusCode; v != http.StatusGone {
 		t.Errorf("Status code mismatch. Expected: %d, got: %d", http.StatusGone, v)
 	}
 }
 
-func TestWriteErrorResponseSetsBodyCorrectly(t *testing.T) {
+func TestErrorJSONSetsBodyCorrectly(t *testing.T) {
 	expectedReason := "Something Not Found"
 	w := httptest.NewRecorder()
 
-	srverrors.WriteErrorResponse(http.StatusNotFound, expectedReason, w)
+	srverrors.ErrorJSON(w, expectedReason, http.StatusNotFound)
 
 	errMsg := srverrors.ServerErrMessage{}
 	if bodyBytes, err := ioutil.ReadAll(w.Result().Body); err != nil {