Move NoteApp tests to Jest

app/assets/javascripts/gfm_auto_complete.js

 import $ from 'jquery';
+import 'at.js';
 import _ from 'underscore';
 import glRegexp from './lib/utils/regexp';
 import AjaxCache from './lib/utils/ajax_cache';

app/assets/javascripts/notes/components/noteable_note.vue

@@ -10,7 +10,7 @@ import Flash from '../../flash';
 import userAvatarLink from '../../vue_shared/components/user_avatar/user_avatar_link.vue';
 import noteHeader from './note_header.vue';
 import noteActions from './note_actions.vue';
-import noteBody from './note_body.vue';
+import NoteBody from './note_body.vue';
 import eventHub from '../event_hub';
 import noteable from '../mixins/noteable';
 import resolvable from '../mixins/resolvable';
@@ -21,7 +21,7 @@ export default {
     userAvatarLink,
     noteHeader,
     noteActions,
-    noteBody,
+    NoteBody,
     TimelineEntryItem,
   },
   mixins: [noteable, resolvable, draftMixin],
@@ -209,7 +209,10 @@ export default {
       // we need to do this to prevent noteForm inconsistent content warning
       // this is something we intentionally do so we need to recover the content
       this.note.note = noteText;
-      this.$refs.noteBody.note.note = noteText;
+      const { noteBody } = this.$refs;
+      if (noteBody) {
+        noteBody.note.note = noteText;
+      }
     },
   },
 };

app/assets/javascripts/notes/components/notes_app.vue

@@ -127,6 +127,9 @@ export default {
       initUserPopovers(this.$el.querySelectorAll('.js-user-link'));
     });
   },
+  beforeDestroy() {
+    this.stopPolling();
+  },
   methods: {
     ...mapActions([
       'setLoadingState',
@@ -144,6 +147,7 @@ export default {
       'expandDiscussion',
       'startTaskList',
       'convertToDiscussion',
+      'stopPolling',
     ]),
     fetchNotes() {
       if (this.isFetching) return null;

spec/frontend/helpers/jquery.js

+import $ from 'jquery';
+
+global.$ = $;
+global.jQuery = $;
+
+export default $;