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)
 }