MM-53924 - Implement NotificationWillBePushed plugin hook (#24263)

* add NotificationWillBePushed hook

* mocks

* use a struct for hook parameters; simplify number of parameters sent across RPC

* missing wg.Wait

* change to a bool return value

server/channels/app/plugin_hooks_test.go

@@ -6,11 +6,14 @@ package app
 import (
 	"bytes"
 	"context"
+	_ "embed"
+	"fmt"
 	"io"
 	"net/http"
 	"net/http/httptest"
 	"os"
 	"path/filepath"
+	"sync"
 	"testing"
 	"time"
 
@@ -1331,3 +1334,118 @@ func TestHookOnCloudLimitsUpdated(t *testing.T) {
 
 	require.True(t, hookCalled)
 }
+
+//go:embed test_templates/hook_notification_will_be_pushed.tmpl
+var hookNotificationWillBePushedTmpl string
+
+func TestHookNotificationWillBePushed(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping TestHookNotificationWillBePushed test in short mode")
+	}
+
+	tests := []struct {
+		name                  string
+		testCode              string
+		expectedNotifications int
+	}{
+		{
+			name:                  "successfully pushed",
+			testCode:              `return false`,
+			expectedNotifications: 6,
+		},
+		{
+			name:                  "push notification rejected",
+			testCode:              `return true`,
+			expectedNotifications: 0,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			th := Setup(t).InitBasic()
+			defer th.TearDown()
+
+			templatedPlugin := fmt.Sprintf(hookNotificationWillBePushedTmpl, tt.testCode)
+			tearDown, _, _ := SetAppEnvironmentWithPlugins(t, []string{templatedPlugin}, th.App, th.NewPluginAPI)
+			defer tearDown()
+
+			// Create 3 users, each having 2 sessions.
+			type userSession struct {
+				user    *model.User
+				session *model.Session
+			}
+			var userSessions []userSession
+			for i := 0; i < 3; i++ {
+				u := th.CreateUser()
+				sess, err := th.App.CreateSession(&model.Session{
+					UserId:    u.Id,
+					DeviceId:  "deviceID" + u.Id,
+					ExpiresAt: model.GetMillis() + 100000,
+				})
+				require.Nil(t, err)
+				// We don't need to track the 2nd session.
+				_, err = th.App.CreateSession(&model.Session{
+					UserId:    u.Id,
+					DeviceId:  "deviceID" + u.Id,
+					ExpiresAt: model.GetMillis() + 100000,
+				})
+				require.Nil(t, err)
+				_, err = th.App.AddTeamMember(th.Context, th.BasicTeam.Id, u.Id)
+				require.Nil(t, err)
+				th.AddUserToChannel(u, th.BasicChannel)
+				userSessions = append(userSessions, userSession{
+					user:    u,
+					session: sess,
+				})
+			}
+
+			handler := &testPushNotificationHandler{
+				t:        t,
+				behavior: "simple",
+			}
+			pushServer := httptest.NewServer(
+				http.HandlerFunc(handler.handleReq),
+			)
+			defer pushServer.Close()
+
+			th.App.UpdateConfig(func(cfg *model.Config) {
+				*cfg.EmailSettings.PushNotificationContents = model.GenericNotification
+				*cfg.EmailSettings.PushNotificationServer = pushServer.URL
+			})
+
+			var wg sync.WaitGroup
+			for _, data := range userSessions {
+				wg.Add(1)
+				go func(user model.User) {
+					defer wg.Done()
+					notification := &PostNotification{
+						Post:    th.CreatePost(th.BasicChannel),
+						Channel: th.BasicChannel,
+						ProfileMap: map[string]*model.User{
+							user.Id: &user,
+						},
+						Sender: &user,
+					}
+					th.App.sendPushNotification(notification, &user, true, false, model.CommentsNotifyAny)
+				}(*data.user)
+			}
+			wg.Wait()
+
+			// Hack to let the worker goroutines complete.
+			time.Sleep(1 * time.Second)
+			// Server side verification.
+			assert.Equal(t, tt.expectedNotifications, handler.numReqs())
+			var numMessages int
+			for _, n := range handler.notifications() {
+				switch n.Type {
+				case model.PushTypeMessage:
+					numMessages++
+					assert.Equal(t, th.BasicChannel.Id, n.ChannelId)
+					assert.Contains(t, n.Message, "mentioned you")
+				default:
+					assert.Fail(t, "should not receive any other push notification types")
+				}
+			}
+			assert.Equal(t, tt.expectedNotifications, numMessages)
+		})
+	}
+}