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_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
+}