Add unit tests for MakeNotifierWrapper

- fixes issue where result was assigned to value rather than
to pointer reference.

Signed-off-by: Alex Ellis (VMware) <alexellis2@gmail.com>

gateway/handlers/notifier_handler.go

@@ -13,32 +13,43 @@ func MakeNotifierWrapper(next http.HandlerFunc, notifiers []HTTPNotifier) http.H
 	return func(w http.ResponseWriter, r *http.Request) {
 		then := time.Now()
 
-		writer := newCustomWriter(w)
-		next(w, r)
+		writer := newWriteInterceptor(w)
+		next(&writer, r)
 
 		url := r.URL.String()
 		for _, notifier := range notifiers {
-			notifier.Notify(r.Method, url, url, writer.CapturedStatusCode, time.Since(then))
+			notifier.Notify(r.Method, url, url, writer.Status(), time.Since(then))
 		}
 	}
 }
 
-func newCustomWriter(w http.ResponseWriter) customWriter {
-	return customWriter{
+func newWriteInterceptor(w http.ResponseWriter) writeInterceptor {
+	return writeInterceptor{
 		w: w,
 	}
 }
 
-type customWriter struct {
+type writeInterceptor struct {
 	CapturedStatusCode int
 	w                  http.ResponseWriter
 }
 
-func (c *customWriter) Write(data []byte) (int, error) {
+func (c *writeInterceptor) Status() int {
+	if c.CapturedStatusCode == 0 {
+		return http.StatusOK
+	}
+	return c.CapturedStatusCode
+}
+
+func (c *writeInterceptor) Header() http.Header {
+	return c.w.Header()
+}
+
+func (c *writeInterceptor) Write(data []byte) (int, error) {
 	return c.w.Write(data)
 }
 
-func (c *customWriter) WriteHeader(code int) {
+func (c *writeInterceptor) WriteHeader(code int) {
 	c.CapturedStatusCode = code
 	c.w.WriteHeader(code)
 }

gateway/handlers/notifier_wrapper_test.go

@@ -0,0 +1,89 @@
+// Copyright (c) OpenFaaS Author(s) 2018. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+package handlers
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+)
+
+func Test_MakeNotifierWrapper_ReceivesHttpStatusInNotifier(t *testing.T) {
+	notifier := &testNotifier{}
+	handlerVisited := false
+	handlerWant := http.StatusAccepted
+
+	handler := MakeNotifierWrapper(func(w http.ResponseWriter, r *http.Request) {
+		handlerVisited = true
+		w.WriteHeader(handlerWant)
+	}, []HTTPNotifier{notifier})
+
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	rec := httptest.NewRecorder()
+
+	handler.ServeHTTP(rec, req)
+
+	if handlerVisited != true {
+		t.Errorf("expected handler to have been visited")
+	}
+
+	if notifier.StatusReceived == 0 {
+		t.Errorf("notifier wanted a status, but got none")
+		t.Fail()
+		return
+	}
+
+	if rec.Result().StatusCode != handlerWant {
+		t.Errorf("recorder status want: %d, got %d", handlerWant, rec.Result().StatusCode)
+	}
+
+	if notifier.StatusReceived != handlerWant {
+		t.Errorf("notifier status want: %d, got %d", handlerWant, notifier.StatusReceived)
+	}
+
+}
+
+func Test_MakeNotifierWrapper_ReceivesDefaultHttpStatusWhenNotSet(t *testing.T) {
+	notifier := &testNotifier{}
+	handlerVisited := false
+	handlerWant := http.StatusOK
+
+	handler := MakeNotifierWrapper(func(w http.ResponseWriter, r *http.Request) {
+		handlerVisited = true
+	}, []HTTPNotifier{notifier})
+
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	rec := httptest.NewRecorder()
+
+	handler.ServeHTTP(rec, req)
+
+	if handlerVisited != true {
+		t.Errorf("expected handler to have been visited")
+	}
+
+	if notifier.StatusReceived == 0 {
+		t.Errorf("notifier wanted a status, but got none")
+		t.Fail()
+		return
+	}
+
+	if rec.Result().StatusCode != handlerWant {
+		t.Errorf("recorder status want: %d, got %d", handlerWant, rec.Result().StatusCode)
+	}
+
+	if notifier.StatusReceived != handlerWant {
+		t.Errorf("notifier status want: %d, got %d", handlerWant, notifier.StatusReceived)
+	}
+
+}
+
+type testNotifier struct {
+	StatusReceived int
+}
+
+// Notify about service metrics
+func (tf *testNotifier) Notify(method string, URL string, originalURL string, statusCode int, duration time.Duration) {
+	tf.StatusReceived = statusCode
+}