From 597e03a6bc2984ff048bfafc368771f22cf01bde Mon Sep 17 00:00:00 2001
From: Elias Nahum <nahumhbl@gmail.com>
Date: Tue, 5 May 2020 18:56:58 -0400
Subject: [PATCH] MM-24852 ensure only one listener for in-app notification is
 registered (#4267)

---
 app/init/global_event_handler.js      |  8 ++++++-
 app/init/global_event_handler.test.js | 33 +++++++++++++++++++++++++--
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/app/init/global_event_handler.js b/app/init/global_event_handler.js
index 2ca97e36b..f02ec4109 100644
--- a/app/init/global_event_handler.js
+++ b/app/init/global_event_handler.js
@@ -45,6 +45,8 @@ const PROMPT_IN_APP_PIN_CODE_AFTER = 5 * 1000;
 
 class GlobalEventHandler {
     constructor() {
+        this.pushNotificationListener = false;
+
         EventEmitter.on(NavigationTypes.NAVIGATION_RESET, this.onLogout);
         EventEmitter.on(NavigationTypes.RESTART_APP, this.onRestartApp);
         EventEmitter.on(General.SERVER_VERSION_CHANGED, this.onServerVersionChanged);
@@ -326,10 +328,14 @@ class GlobalEventHandler {
     };
 
     turnOnInAppNotificationHandling = () => {
-        EventEmitter.on(ViewTypes.NOTIFICATION_IN_APP, this.handleInAppNotification);
+        if (!this.pushNotificationListener) {
+            this.pushNotificationListener = true;
+            EventEmitter.on(ViewTypes.NOTIFICATION_IN_APP, this.handleInAppNotification);
+        }
     }
 
     turnOffInAppNotificationHandling = () => {
+        this.pushNotificationListener = false;
         EventEmitter.off(ViewTypes.NOTIFICATION_IN_APP, this.handleInAppNotification);
     }
 
diff --git a/app/init/global_event_handler.test.js b/app/init/global_event_handler.test.js
index 49047b957..898661778 100644
--- a/app/init/global_event_handler.test.js
+++ b/app/init/global_event_handler.test.js
@@ -9,6 +9,7 @@ import semver from 'semver/preload';
 import PushNotification from 'app/push_notifications';
 import mattermostBucket from 'app/mattermost_bucket';
 import * as I18n from '@i18n';
+import EventEmitter from '@mm-redux/utils/event_emitter';
 import Store from '@store/store';
 import intitialState from '@store/initial_state';
 
@@ -22,7 +23,7 @@ jest.mock('app/init/credentials', () => ({
     removeAppCredentials: jest.fn(),
 }));
 
-jest.mock('app/utils/error_handling', () => ({
+jest.mock('@utils/error_handling', () => ({
     default: {
         initializeErrorHandling: jest.fn(),
     },
@@ -45,7 +46,7 @@ jest.mock('@mm-redux/actions/general', () => ({
     setServerVersion: jest.fn().mockReturnValue('setServerVersion'),
 }));
 
-jest.mock('app/actions/views/root', () => ({
+jest.mock('@actions/views/root', () => ({
     startDataCleanup: jest.fn(),
     loadConfigAndLicense: jest.fn().mockReturnValue('loadConfigAndLicense'),
 }));
@@ -123,6 +124,34 @@ describe('GlobalEventHandler', () => {
         expect(setUserTimezone).toHaveBeenCalledTimes(1);
     });
 
+    it('should register NOTIFICATION_IN_APP once', () => {
+        const on = jest.spyOn(EventEmitter, 'on');
+
+        // Reset the listener
+        GlobalEventHandler.pushNotificationListener = false;
+
+        GlobalEventHandler.turnOnInAppNotificationHandling();
+
+        // call it a second time
+        GlobalEventHandler.turnOnInAppNotificationHandling();
+
+        expect(on).toBeCalledTimes(1);
+        expect(on).toBeCalledWith('NOTIFICATION_IN_APP', GlobalEventHandler.handleInAppNotification);
+    });
+
+    it('should register NOTIFICATION_IN_APP once after unregister', () => {
+        const on = jest.spyOn(EventEmitter, 'on');
+        GlobalEventHandler.turnOnInAppNotificationHandling();
+        GlobalEventHandler.turnOffInAppNotificationHandling();
+
+        // call it a second time
+        GlobalEventHandler.turnOnInAppNotificationHandling();
+        GlobalEventHandler.turnOnInAppNotificationHandling();
+
+        expect(on).toBeCalledTimes(1);
+        expect(on).toBeCalledWith('NOTIFICATION_IN_APP', GlobalEventHandler.handleInAppNotification);
+    });
+
     describe('onServerVersionChanged', () => {
         beforeEach(() => {
             jest.clearAllMocks();