init commentPreview migration (#19090)

app/assets/javascripts/initializePage.js

@@ -3,8 +3,7 @@
   initializeAllTagEditButtons, initializeUserFollowButts,
   initializeCommentsPage,
   initializeArticleDate, initializeArticleReactions, initNotifications,
-  initializeSettings,
-  initializeCommentPreview, initializeRuntimeBanner,
+  initializeSettings, initializeRuntimeBanner,
   initializeTimeFixer, initializeDashboardSort,
   initializeArchivedPostFilter, initializeCreditsPage,
   initializeProfileInfoToggle, initializeDrawerSliders,
@@ -21,7 +20,6 @@ function callInitializers() {
   initializeArticleReactions();
   initNotifications();
   initializeSettings();
-  initializeCommentPreview();
   initializeTimeFixer();
   initializeDashboardSort();
   initializeArchivedPostFilter();

app/javascript/packs/baseInitializers.js

@@ -1,3 +1,5 @@
-import { initializeCommentDate } from "./initializers/initializeCommentDate";
+import { initializeCommentDate } from './initializers/initializeCommentDate';
+import { initializeCommentPreview } from './initializers/initializeCommentPreview';
 
-initializeCommentDate();
+initializeCommentDate();
+initializeCommentPreview();

app/javascript/packs/initializers/__tests__/initializeCommentPreview.test.js

@@ -0,0 +1,17 @@
+import { initializeCommentPreview } from '../initializeCommentPreview';
+
+describe('initializeCommentPreview', () => {
+  beforeEach(() => {
+    const button = document.createElement('button');
+    button.classList.add('preview-toggle');
+  });
+
+  test('should call event listener when preview button exist', async () => {
+    const button = document.createElement('button');
+    button.classList.add('preview-toggle');
+    button.addEventListener = jest.fn();
+    initializeCommentPreview();
+
+    expect(button.addEventListener).not.toHaveBeenCalled();
+  });
+});

app/javascript/packs/initializers/initializeCommentPreview.js

@@ -57,7 +57,7 @@ function handleCommentPreview(event) {
   }
 }
 
-function initializeCommentPreview() {
+export function initializeCommentPreview() {
   const previewButton = document.getElementsByClassName('preview-toggle')[0];
 
   if (!previewButton) {