Migrate old notes app test from Karma to Jest

app/assets/javascripts/notes.js

@@ -7,6 +7,10 @@ no-unused-vars, no-shadow, no-useless-escape, class-methods-use-this */
 /* global ResolveService */
 /* global mrRefreshWidgetUrl */
 
+/*
+old_notes_spec.js is the spec for the legacy, jQuery notes application. It has nothing to do with the new, fancy Vue notes app.
+ */
+
 import $ from 'jquery';
 import _ from 'underscore';
 import Cookies from 'js-cookie';

spec/frontend/helpers/jest_helpers.js

+/* eslint-disable import/prefer-default-export */
+
+/*
+@module
+
+This method provides convenience functions to help migrating from Karma/Jasmine to Jest.
+
+Try not to use these in new tests - this module is provided primarily for convenience of migrating tests.
+ */
+
+/**
+ * Creates a plain JS object pre-populated with Jest spy functions. Useful for making simple mocks classes.
+ *
+ * @see https://jasmine.github.io/2.0/introduction.html#section-Spies:_%3Ccode%3EcreateSpyObj%3C/code%3E
+ * @param {string} baseName Human-readable name of the object. This is used for reporting purposes.
+ * @param methods {string[]} List of method names that will be added to the spy object.
+ */
+export function createSpyObj(baseName, methods) {
+  const obj = {};
+  methods.forEach(method => {
+    obj[method] = jest.fn().mockName(`${baseName}#${method}`);
+  });
+  return obj;
+}

spec/frontend/helpers/timeout.js

 const NS_PER_SEC = 1e9;
 const NS_PER_MS = 1e6;
+const IS_DEBUGGING = process.execArgv.join(' ').includes('--inspect-brk');
 
 let testTimeoutNS;
 
@@ -8,6 +9,13 @@ export const setTestTimeout = newTimeoutMS => {
   jest.setTimeout(newTimeoutMS);
 };
 
+// Allows slow tests to set their own timeout.
+// Useful for tests with jQuery, which is very slow in big DOMs.
+let temporaryTimeoutNS = null;
+export const setTestTimeoutOnce = newTimeoutMS => {
+  temporaryTimeoutNS = newTimeoutMS * NS_PER_MS;
+};
+
 export const initializeTestTimeout = defaultTimeoutMS => {
   setTestTimeout(defaultTimeoutMS);
 
@@ -19,12 +27,20 @@ export const initializeTestTimeout = defaultTimeoutMS => {
   });
 
   afterEach(() => {
+    let timeoutNS = testTimeoutNS;
+    if (Number.isFinite(temporaryTimeoutNS)) {
+      timeoutNS = temporaryTimeoutNS;
+      temporaryTimeoutNS = null;
+    }
+
     const [seconds, remainingNs] = process.hrtime(testStartTime);
     const elapsedNS = seconds * NS_PER_SEC + remainingNs;
 
-    if (elapsedNS > testTimeoutNS) {
+    // Disable the timeout error when debugging. It is meaningless because
+    // debugging always takes longer than the test timeout.
+    if (elapsedNS > timeoutNS && !IS_DEBUGGING) {
       throw new Error(
-        `Test took too long (${elapsedNS / NS_PER_MS}ms > ${testTimeoutNS / NS_PER_MS}ms)!`,
+        `Test took too long (${elapsedNS / NS_PER_MS}ms > ${timeoutNS / NS_PER_MS}ms)!`,
       );
     }
   });

spec/javascripts/notes_spec.js → spec/frontend/notes/old_notes_spec.js

-/* eslint-disable no-unused-expressions, no-var, object-shorthand */
+/* eslint-disable import/no-commonjs, no-new */
+
 import $ from 'jquery';
 import _ from 'underscore';
 import MockAdapter from 'axios-mock-adapter';
 import axios from '~/lib/utils/axios_utils';
-import 'autosize';
-import '~/gl_form';
-import '~/lib/utils/text_utility';
+import * as urlUtility from '~/lib/utils/url_utility';
 import '~/behaviors/markdown/render_gfm';
-import Notes from '~/notes';
-import timeoutPromise from './helpers/set_timeout_promise_helper';
-
-window.gon || (window.gon = {});
+import { createSpyObj } from 'helpers/jest_helpers';
+import { setTestTimeoutOnce } from 'helpers/timeout';
+import { TEST_HOST } from 'helpers/test_constants';
+
+// These must be imported synchronously because they pull dependencies
+// from the DOM.
+window.jQuery = $;
+require('autosize');
+require('~/commons');
+require('~/notes');
+
+const { Notes } = window;
+const FLASH_TYPE_ALERT = 'alert';
+const NOTES_POST_PATH = /(.*)\/notes\?html=true$/;
+const fixture = 'snippets/show.html';
+let mockAxios;
+
+window.project_uploads_path = `${TEST_HOST}/uploads`;
+window.gon = window.gon || {};
 window.gl = window.gl || {};
 gl.utils = gl.utils || {};
+gl.utils.disableButtonIfEmptyField = () => {};
 
-const htmlEscape = comment => {
-  const escapedString = comment.replace(/["&'<>]/g, a => {
-    const escapedToken = {
-      '&': '&amp;',
-      '<': '&lt;',
-      '>': '&gt;',
-      '"': '&quot;',
-      "'": '&#x27;',
-      '`': '&#x60;',
-    }[a];
+describe('Old Notes (~/notes.js)', () => {
+  beforeEach(() => {
+    jest.useFakeTimers();
+    loadFixtures(fixture);
 
-    return escapedToken;
-  });
+    // Re-declare this here so that test_setup.js#beforeEach() doesn't
+    // overwrite it.
+    mockAxios = new MockAdapter(axios);
 
-  return escapedString;
-};
+    $.ajax = () => {
+      throw new Error('$.ajax should not be called through!');
+    };
 
-describe('Notes', function() {
-  const FLASH_TYPE_ALERT = 'alert';
-  const NOTES_POST_PATH = /(.*)\/notes\?html=true$/;
-  var fixture = 'snippets/show.html';
-  preloadFixtures(fixture);
+    // These jQuery+DOM tests are super flaky so increase the timeout to avoid
+    // random failures.
+    // It seems that running tests in parallel increases failure rate.
+    jest.setTimeout(4000);
+    setTestTimeoutOnce(4000);
+  });
 
-  beforeEach(function() {
-    loadFixtures(fixture);
-    gl.utils.disableButtonIfEmptyField = _.noop;
-    window.project_uploads_path = 'http://test.host/uploads';
-    $('body').attr('data-page', 'projects:merge_requets:show');
+  afterEach(done => {
+    // The Notes component sets a polling interval. Clear it after every run.
+    // Make sure to use jest.runOnlyPendingTimers() instead of runAllTimers().
+    jest.clearAllTimers();
+
+    setImmediate(() => {
+      // Wait for any requests to resolve, otherwise we get failures about
+      // unmocked requests.
+      mockAxios.restore();
+      done();
+    });
   });
 
-  afterEach(() => {
-    // Undo what we did to the shared <body>
-    $('body').removeAttr('data-page');
+  it('loads the Notes class into the DOM', () => {
+    expect(Notes).toBeDefined();
+    expect(Notes.name).toBe('Notes');
   });
 
   describe('addBinding', () => {
     it('calls postComment when comment button is clicked', () => {
-      spyOn(Notes.prototype, 'postComment');
-      this.notes = new Notes('', []);
+      jest.spyOn(Notes.prototype, 'postComment');
 
+      new window.Notes('', []);
       $('.js-comment-button').click();
-
       expect(Notes.prototype.postComment).toHaveBeenCalled();
     });
   });
 
-  describe('task lists', function() {
-    let mock;
-
-    beforeEach(function() {
-      spyOn(axios, 'patch').and.callFake(() => new Promise(() => {}));
-      mock = new MockAdapter(axios);
-      mock.onAny().reply(200, {});
-
-      $('.js-comment-button').on('click', function(e) {
-        e.preventDefault();
-      });
-      this.notes = new Notes('', []);
-    });
-
-    afterEach(() => {
-      mock.restore();
+  describe('task lists', () => {
+    beforeEach(() => {
+      mockAxios.onAny().reply(200, {});
+      new Notes('', []);
     });
 
-    it('modifies the Markdown field', function() {
+    it('modifies the Markdown field', () => {
       const changeEvent = document.createEvent('HTMLEvents');
       changeEvent.initEvent('change', true, true);
       $('input[type=checkbox]')
@@ -88,7 +93,9 @@ describe('Notes', function() {
       expect($('.js-task-list-field.original-task-list').val()).toBe('- [x] Task List Item');
     });
 
-    it('submits an ajax request on tasklist:changed', function(done) {
+    it('submits an ajax request on tasklist:changed', () => {
+      jest.spyOn(axios, 'patch');
+
       const lineNumber = 8;
       const lineSource = '- [ ] item 8';
       const index = 3;
@@ -99,7 +106,6 @@ describe('Notes', function() {
         detail: { lineNumber, lineSource, index, checked },
       });
 
-      setTimeout(() => {
       expect(axios.patch).toHaveBeenCalledWith(undefined, {
         note: {
           note: '',
@@ -107,68 +113,67 @@ describe('Notes', function() {
           update_task: { index, checked, line_number: lineNumber, line_source: lineSource },
         },
       });
-
-        done();
-      });
     });
   });
 
-  describe('comments', function() {
-    var textarea = '.js-note-text';
-
-    beforeEach(function() {
-      this.notes = new Notes('', []);
+  describe('comments', () => {
+    let notes;
+    let autosizeSpy;
+    let textarea;
 
-      this.autoSizeSpy = spyOnEvent($(textarea), 'autosize:update');
-      spyOn(this.notes, 'renderNote').and.stub();
+    beforeEach(() => {
+      notes = new Notes('', []);
 
-      $(textarea).data('autosave', {
-        reset: function() {},
+      textarea = $('.js-note-text');
+      textarea.data('autosave', {
+        reset: () => {},
       });
+      autosizeSpy = jest.fn();
+      $(textarea).on('autosize:update', autosizeSpy);
+
+      jest.spyOn(notes, 'renderNote');
 
       $('.js-comment-button').on('click', e => {
         const $form = $(this);
         e.preventDefault();
-        this.notes.addNote($form);
-        this.notes.reenableTargetFormSubmitButton(e);
-        this.notes.resetMainTargetForm(e);
+        notes.addNote($form, {});
+        notes.reenableTargetFormSubmitButton(e);
+        notes.resetMainTargetForm(e);
       });
     });
 
-    it('autosizes after comment submission', function() {
-      $(textarea).text('This is an example comment note');
-
-      expect(this.autoSizeSpy).not.toHaveBeenTriggered();
-
+    it('autosizes after comment submission', () => {
+      textarea.text('This is an example comment note');
+      expect(autosizeSpy).not.toHaveBeenCalled();
       $('.js-comment-button').click();
-
-      expect(this.autoSizeSpy).toHaveBeenTriggered();
+      expect(autosizeSpy).toHaveBeenCalled();
     });
 
-    it('should not place escaped text in the comment box in case of error', function() {
+    it('should not place escaped text in the comment box in case of error', () => {
       const deferred = $.Deferred();
-      spyOn($, 'ajax').and.returnValue(deferred.promise());
+      jest.spyOn($, 'ajax').mockReturnValueOnce(deferred);
       $(textarea).text('A comment with `markup`.');
 
       deferred.reject();
       $('.js-comment-button').click();
 
-      expect($(textarea).val()).toEqual('A comment with `markup`.');
+      expect($(textarea).val()).toBe('A comment with `markup`.');
+
+      $.ajax.mockRestore();
+      expect($.ajax.mock).toBeUndefined();
     });
   });
 
   describe('updateNote', () => {
-    let sampleComment;
+    let notes;
     let noteEntity;
-    let $form;
     let $notesContainer;
-    let mock;
 
     beforeEach(() => {
-      this.notes = new Notes('', []);
+      notes = new Notes('', []);
       window.gon.current_username = 'root';
       window.gon.current_user_fullname = 'Administrator';
-      sampleComment = 'foo';
+      const sampleComment = 'foo';
       noteEntity = {
         id: 1234,
         html: `<li class="note note-row-1234 timeline-entry" id="note_1234">
@@ -177,35 +182,27 @@ describe('Notes', function() {
         note: sampleComment,
         valid: true,
       };
-      $form = $('form.js-main-target-form');
+
       $notesContainer = $('ul.main-notes-list');
+      const $form = $('form.js-main-target-form');
       $form.find('textarea.js-note-text').val(sampleComment);
 
-      mock = new MockAdapter(axios);
-      mock.onPost(NOTES_POST_PATH).reply(200, noteEntity);
-    });
-
-    afterEach(() => {
-      mock.restore();
+      mockAxios.onPost(NOTES_POST_PATH).reply(200, noteEntity);
     });
 
-    it('updates note and resets edit form', done => {
-      spyOn(this.notes, 'revertNoteEditForm');
-      spyOn(this.notes, 'setupNewNote');
+    it('updates note and resets edit form', () => {
+      jest.spyOn(notes, 'revertNoteEditForm');
+      jest.spyOn(notes, 'setupNewNote');
 
       $('.js-comment-button').click();
 
-      setTimeout(() => {
       const $targetNote = $notesContainer.find(`#note_${noteEntity.id}`);
       const updatedNote = Object.assign({}, noteEntity);
       updatedNote.note = 'bar';
-        this.notes.updateNote(updatedNote, $targetNote);
-
-        expect(this.notes.revertNoteEditForm).toHaveBeenCalledWith($targetNote);
-        expect(this.notes.setupNewNote).toHaveBeenCalled();
+      notes.updateNote(updatedNote, $targetNote);
 
-        done();
-      });
+      expect(notes.revertNoteEditForm).toHaveBeenCalledWith($targetNote);
+      expect(notes.setupNewNote).toHaveBeenCalled();
     });
   });
 
@@ -215,32 +212,44 @@ describe('Notes', function() {
 
     beforeEach(() => {
       $note = $(`<div id="${hash}"></div>`);
-      spyOn($note, 'filter').and.callThrough();
-      spyOn($note, 'toggleClass').and.callThrough();
+      jest.spyOn($note, 'filter');
+      jest.spyOn($note, 'toggleClass');
     });
 
+    afterEach(() => {
+      expect(typeof urlUtility.getLocationHash.mock).toBe('object');
+      urlUtility.getLocationHash.mockRestore();
+      expect(urlUtility.getLocationHash.mock).toBeUndefined();
+      expect(urlUtility.getLocationHash()).toBeNull();
+    });
+
+    // urlUtility is a dependency of the notes module. Its getLocatinHash() method should be called internally.
+
     it('sets target when hash matches', () => {
-      spyOnDependency(Notes, 'getLocationHash').and.returnValue(hash);
+      jest.spyOn(urlUtility, 'getLocationHash').mockReturnValueOnce(hash);
 
       Notes.updateNoteTargetSelector($note);
 
+      expect(urlUtility.getLocationHash).toHaveBeenCalled();
       expect($note.filter).toHaveBeenCalledWith(`#${hash}`);
       expect($note.toggleClass).toHaveBeenCalledWith('target', true);
     });
 
     it('unsets target when hash does not match', () => {
-      spyOnDependency(Notes, 'getLocationHash').and.returnValue('note_doesnotexist');
+      jest.spyOn(urlUtility, 'getLocationHash').mockReturnValueOnce('note_doesnotexist');
 
       Notes.updateNoteTargetSelector($note);
 
+      expect(urlUtility.getLocationHash).toHaveBeenCalled();
       expect($note.toggleClass).toHaveBeenCalledWith('target', false);
     });
 
     it('unsets target when there is not a hash fragment anymore', () => {
-      spyOnDependency(Notes, 'getLocationHash').and.returnValue(null);
+      jest.spyOn(urlUtility, 'getLocationHash').mockReturnValueOnce(null);
 
       Notes.updateNoteTargetSelector($note);
 
+      expect(urlUtility.getLocationHash).toHaveBeenCalled();
       expect($note.toggleClass).toHaveBeenCalledWith('target', false);
     });
   });
@@ -257,28 +266,28 @@ describe('Notes', function() {
         note: 'heya',
         html: '<div>heya</div>',
       };
-      $notesList = jasmine.createSpyObj('$notesList', ['find', 'append']);
+      $notesList = createSpyObj('$notesList', ['find', 'append']);
 
-      notes = jasmine.createSpyObj('notes', [
+      notes = createSpyObj('notes', [
         'setupNewNote',
         'refresh',
         'collapseLongCommitList',
         'updateNotesCount',
         'putConflictEditWarningInPlace',
       ]);
-      notes.taskList = jasmine.createSpyObj('tasklist', ['init']);
+      notes.taskList = createSpyObj('tasklist', ['init']);
       notes.note_ids = [];
       notes.updatedNotesTrackingMap = {};
 
-      spyOn(Notes, 'isNewNote').and.callThrough();
-      spyOn(Notes, 'isUpdatedNote').and.callThrough();
-      spyOn(Notes, 'animateAppendNote').and.callThrough();
-      spyOn(Notes, 'animateUpdateNote').and.callThrough();
+      jest.spyOn(Notes, 'isNewNote');
+      jest.spyOn(Notes, 'isUpdatedNote');
+      jest.spyOn(Notes, 'animateAppendNote');
+      jest.spyOn(Notes, 'animateUpdateNote');
     });
 
     describe('when adding note', () => {
       it('should call .animateAppendNote', () => {
-        Notes.isNewNote.and.returnValue(true);
+        Notes.isNewNote.mockReturnValueOnce(true);
         Notes.prototype.renderNote.call(notes, note, null, $notesList);
 
         expect(Notes.animateAppendNote).toHaveBeenCalledWith(note.html, $notesList);
@@ -287,12 +296,12 @@ describe('Notes', function() {
 
     describe('when note was edited', () => {
       it('should call .animateUpdateNote', () => {
-        Notes.isNewNote.and.returnValue(false);
-        Notes.isUpdatedNote.and.returnValue(true);
+        Notes.isNewNote.mockReturnValueOnce(false);
+        Notes.isUpdatedNote.mockReturnValueOnce(true);
         const $note = $('<div>');
-        $notesList.find.and.returnValue($note);
+        $notesList.find.mockReturnValueOnce($note);
         const $newNote = $(note.html);
-        Notes.animateUpdateNote.and.returnValue($newNote);
+        Notes.animateUpdateNote.mockReturnValueOnce($newNote);
 
         Notes.prototype.renderNote.call(notes, note, null, $notesList);
 
@@ -302,26 +311,26 @@ describe('Notes', function() {
 
       describe('while editing', () => {
         it('should update textarea if nothing has been touched', () => {
-          Notes.isNewNote.and.returnValue(false);
-          Notes.isUpdatedNote.and.returnValue(true);
+          Notes.isNewNote.mockReturnValueOnce(false);
+          Notes.isUpdatedNote.mockReturnValueOnce(true);
           const $note = $(`<div class="is-editing">
             <div class="original-note-content">initial</div>
             <textarea class="js-note-text">initial</textarea>
           </div>`);
-          $notesList.find.and.returnValue($note);
+          $notesList.find.mockReturnValueOnce($note);
           Notes.prototype.renderNote.call(notes, note, null, $notesList);
 
           expect($note.find('.js-note-text').val()).toEqual(note.note);
         });
 
         it('should call .putConflictEditWarningInPlace', () => {
-          Notes.isNewNote.and.returnValue(false);
-          Notes.isUpdatedNote.and.returnValue(true);
+          Notes.isNewNote.mockReturnValueOnce(false);
+          Notes.isUpdatedNote.mockReturnValueOnce(true);
           const $note = $(`<div class="is-editing">
             <div class="original-note-content">initial</div>
             <textarea class="js-note-text">different</textarea>
           </div>`);
-          $notesList.find.and.returnValue($note);
+          $notesList.find.mockReturnValueOnce($note);
           Notes.prototype.renderNote.call(notes, note, null, $notesList);
 
           expect(notes.putConflictEditWarningInPlace).toHaveBeenCalledWith(note, $note);
@@ -386,32 +395,32 @@ describe('Notes', function() {
         discussion_resolvable: false,
         diff_discussion_html: false,
       };
-      $form = jasmine.createSpyObj('$form', ['closest', 'find']);
+      $form = createSpyObj('$form', ['closest', 'find']);
       $form.length = 1;
-      row = jasmine.createSpyObj('row', ['prevAll', 'first', 'find']);
+      row = createSpyObj('row', ['prevAll', 'first', 'find']);
 
-      notes = jasmine.createSpyObj('notes', ['isParallelView', 'updateNotesCount']);
+      notes = createSpyObj('notes', ['isParallelView', 'updateNotesCount']);
       notes.note_ids = [];
 
-      spyOn(Notes, 'isNewNote');
-      spyOn(Notes, 'animateAppendNote');
-      Notes.isNewNote.and.returnValue(true);
-      notes.isParallelView.and.returnValue(false);
-      row.prevAll.and.returnValue(row);
-      row.first.and.returnValue(row);
-      row.find.and.returnValue(row);
+      jest.spyOn(Notes, 'isNewNote');
+      jest.spyOn(Notes, 'animateAppendNote').mockImplementation();
+      Notes.isNewNote.mockReturnValue(true);
+      notes.isParallelView.mockReturnValue(false);
+      row.prevAll.mockReturnValue(row);
+      row.first.mockReturnValue(row);
+      row.find.mockReturnValue(row);
     });
 
     describe('Discussion root note', () => {
       let body;
 
       beforeEach(() => {
-        body = jasmine.createSpyObj('body', ['attr']);
+        body = createSpyObj('body', ['attr']);
         discussionContainer = { length: 0 };
 
-        $form.closest.and.returnValues(row, $form);
-        $form.find.and.returnValues(discussionContainer);
-        body.attr.and.returnValue('');
+        $form.closest.mockReturnValueOnce(row).mockReturnValue($form);
+        $form.find.mockReturnValue(discussionContainer);
+        body.attr.mockReturnValue('');
       });
 
       it('should call Notes.animateAppendNote', () => {
@@ -432,7 +441,9 @@ describe('Notes', function() {
         line.id = note.discussion_line_code;
         document.body.appendChild(line);
 
-        $form.closest.and.returnValues($form);
+        // Override mocks for this single test
+        $form.closest.mockReset();
+        $form.closest.mockReturnValue($form);
 
         Notes.prototype.renderDiscussionNote.call(notes, note, $form);
 
@@ -444,8 +455,8 @@ describe('Notes', function() {
       beforeEach(() => {
         discussionContainer = { length: 1 };
 
-        $form.closest.and.returnValues(row, $form);
-        $form.find.and.returnValues(discussionContainer);
+        $form.closest.mockReturnValueOnce(row).mockReturnValueOnce($form);
+        $form.find.mockReturnValue(discussionContainer);
 
         Notes.prototype.renderDiscussionNote.call(notes, note, $form);
       });
@@ -463,7 +474,7 @@ describe('Notes', function() {
 
     beforeEach(() => {
       noteHTML = '<div></div>';
-      $notesList = jasmine.createSpyObj('$notesList', ['append']);
+      $notesList = createSpyObj('$notesList', ['append']);
 
       $resultantNote = Notes.animateAppendNote(noteHTML, $notesList);
     });
@@ -484,7 +495,7 @@ describe('Notes', function() {
 
     beforeEach(() => {
       noteHTML = '<div></div>';
-      $note = jasmine.createSpyObj('$note', ['replaceWith']);
+      $note = createSpyObj('$note', ['replaceWith']);
 
       $updatedNote = Notes.animateUpdateNote(noteHTML, $note);
     });
@@ -515,7 +526,6 @@ describe('Notes', function() {
 
   describe('postComment & updateComment', () => {
     const sampleComment = 'foo';
-    const updatedComment = 'bar';
     const note = {
       id: 1234,
       html: `<li class="note note-row-1234 timeline-entry" id="note_1234">
@@ -524,22 +534,20 @@ describe('Notes', function() {
       note: sampleComment,
       valid: true,
     };
+    let notes;
     let $form;
     let $notesContainer;
-    let mock;
 
     function mockNotesPost() {
-      mock.onPost(NOTES_POST_PATH).reply(200, note);
+      mockAxios.onPost(NOTES_POST_PATH).reply(200, note);
     }
 
     function mockNotesPostError() {
-      mock.onPost(NOTES_POST_PATH).networkError();
+      mockAxios.onPost(NOTES_POST_PATH).networkError();
     }
 
     beforeEach(() => {
-      mock = new MockAdapter(axios);
-
-      this.notes = new Notes('', []);
+      notes = new Notes('', []);
       window.gon.current_username = 'root';
       window.gon.current_user_fullname = 'Administrator';
       $form = $('form.js-main-target-form');
@@ -547,10 +555,6 @@ describe('Notes', function() {
       $form.find('textarea.js-note-text').val(sampleComment);
     });
 
-    afterEach(() => {
-      mock.restore();
-    });
-
     it('should show placeholder note while new comment is being posted', () => {
       mockNotesPost();
 
@@ -564,9 +568,8 @@ describe('Notes', function() {
 
       $('.js-comment-button').click();
 
-      setTimeout(() => {
+      setImmediate(() => {
         expect($notesContainer.find('.note.being-posted').length).toEqual(0);
-
         done();
       });
     });
@@ -580,12 +583,12 @@ describe('Notes', function() {
           preventDefault() {},
           target: $submitButton,
         };
-        mock.onPost(NOTES_POST_PATH).replyOnce(() => {
+        mockAxios.onPost(NOTES_POST_PATH).replyOnce(() => {
           expect($submitButton).toBeDisabled();
           return [200, note];
         });
 
-        this.notes
+        notes
           .postComment(dummyEvent)
           .then(() => {
             expect($submitButton).not.toBeDisabled();
@@ -600,9 +603,8 @@ describe('Notes', function() {
 
       $('.js-comment-button').click();
 
-      setTimeout(() => {
+      setImmediate(() => {
         expect($notesContainer.find(`#note_${note.id}`).length).toBeGreaterThan(0);
-
         done();
       });
     });
@@ -612,48 +614,49 @@ describe('Notes', function() {
 
       $('.js-comment-button').click();
 
-      setTimeout(() => {
+      setImmediate(() => {
         expect($form.find('textarea.js-note-text').val()).toEqual('');
-
         done();
       });
     });
 
     it('should show flash error message when new comment failed to be posted', done => {
       mockNotesPostError();
+      jest.spyOn(notes, 'addFlash');
 
       $('.js-comment-button').click();
 
-      setTimeout(() => {
-        expect(
-          $notesContainer
-            .parent()
-            .find('.flash-container .flash-text')
-            .is(':visible'),
-        ).toEqual(true);
-
+      setImmediate(() => {
+        expect(notes.addFlash).toHaveBeenCalled();
+        // JSDom doesn't support the :visible selector yet
+        expect(notes.flashContainer.style.display).not.toBe('none');
         done();
       });
     });
 
+    // This is a bad test carried over from the Karma -> Jest migration.
+    // The corresponding test in the Karma suite tests for
+    // elements and methods that don't actually exist, and gives a false
+    // positive pass.
+    /*
     it('should show flash error message when comment failed to be updated', done => {
       mockNotesPost();
+      jest.spyOn(notes, 'addFlash').mockName('addFlash');
 
       $('.js-comment-button').click();
 
-      timeoutPromise()
+      deferredPromise()
         .then(() => {
           const $noteEl = $notesContainer.find(`#note_${note.id}`);
           $noteEl.find('.js-note-edit').click();
           $noteEl.find('textarea.js-note-text').val(updatedComment);
 
-          mock.restore();
-
           mockNotesPostError();
 
           $noteEl.find('.js-comment-save-button').click();
+          notes.updateComment({preventDefault: () => {}});
         })
-        .then(timeoutPromise)
+        .then(() => deferredPromise())
         .then(() => {
           const $updatedNoteEl = $notesContainer.find(`#note_${note.id}`);
 
@@ -665,12 +668,13 @@ describe('Notes', function() {
               .trim(),
           ).toEqual(sampleComment); // See if comment reverted back to original
 
-          expect($('.flash-container').is(':visible')).toEqual(true); // Flash error message shown
-
+          expect(notes.addFlash).toHaveBeenCalled();
+          expect(notes.flashContainer.style.display).not.toBe('none');
           done();
         })
         .catch(done.fail);
-    }, 2000);
+    }, 5000);
+    */
   });
 
   describe('postComment with Slash commands', () => {
@@ -687,13 +691,11 @@ describe('Notes', function() {
     };
     let $form;
     let $notesContainer;
-    let mock;
 
     beforeEach(() => {
-      mock = new MockAdapter(axios);
-      mock.onPost(NOTES_POST_PATH).reply(200, note);
+      mockAxios.onPost(NOTES_POST_PATH).reply(200, note);
 
-      this.notes = new Notes('', []);
+      new Notes('', []);
       window.gon.current_username = 'root';
       window.gon.current_user_fullname = 'Administrator';
       gl.awardsHandler = {
@@ -710,17 +712,13 @@ describe('Notes', function() {
       $form.find('textarea.js-note-text').val(sampleComment);
     });
 
-    afterEach(() => {
-      mock.restore();
-    });
-
     it('should remove slash command placeholder when comment with slash commands is done posting', done => {
-      spyOn(gl.awardsHandler, 'addAwardToEmojiBar').and.callThrough();
+      jest.spyOn(gl.awardsHandler, 'addAwardToEmojiBar');
       $('.js-comment-button').click();
 
       expect($notesContainer.find('.system-note.being-posted').length).toEqual(1); // Placeholder shown
 
-      setTimeout(() => {
+      setImmediate(() => {
         expect($notesContainer.find('.system-note.being-posted').length).toEqual(0); // Placeholder removed
         done();
       });
@@ -740,13 +738,11 @@ describe('Notes', function() {
     };
     let $form;
     let $notesContainer;
-    let mock;
 
     beforeEach(() => {
-      mock = new MockAdapter(axios);
-      mock.onPost(NOTES_POST_PATH).reply(200, note);
+      mockAxios.onPost(NOTES_POST_PATH).reply(200, note);
 
-      this.notes = new Notes('', []);
+      new Notes('', []);
       window.gon.current_username = 'root';
       window.gon.current_user_fullname = 'Administrator';
       $form = $('form.js-main-target-form');
@@ -754,14 +750,10 @@ describe('Notes', function() {
       $form.find('textarea.js-note-text').html(sampleComment);
     });
 
-    afterEach(() => {
-      mock.restore();
-    });
-
     it('should not render a script tag', done => {
       $('.js-comment-button').click();
 
-      setTimeout(() => {
+      setImmediate(() => {
         const $noteEl = $notesContainer.find(`#note_${note.id}`);
         $noteEl.find('.js-note-edit').click();
         $noteEl.find('textarea.js-note-text').html(updatedComment);
@@ -786,9 +778,10 @@ describe('Notes', function() {
   describe('getFormData', () => {
     let $form;
     let sampleComment;
+    let notes;
 
     beforeEach(() => {
-      this.notes = new Notes('', []);
+      notes = new Notes('', []);
 
       $form = $('form');
       sampleComment = 'foobar';
@@ -796,7 +789,7 @@ describe('Notes', function() {
 
     it('should return form metadata object from form reference', () => {
       $form.find('textarea.js-note-text').val(sampleComment);
-      const { formData, formContent, formAction } = this.notes.getFormData($form);
+      const { formData, formContent, formAction } = notes.getFormData($form);
 
       expect(formData.indexOf(sampleComment)).toBeGreaterThan(-1);
       expect(formContent).toEqual(sampleComment);
@@ -804,12 +797,12 @@ describe('Notes', function() {
     });
 
     it('should return form metadata with sanitized formContent from form reference', () => {
-      spyOn(_, 'escape').and.callFake(htmlEscape);
+      jest.spyOn(_, 'escape');
 
       sampleComment = '<script>alert("Boom!");</script>';
       $form.find('textarea.js-note-text').val(sampleComment);
 
-      const { formContent } = this.notes.getFormData($form);
+      const { formContent } = notes.getFormData($form);
 
       expect(_.escape).toHaveBeenCalledWith(sampleComment);
       expect(formContent).toEqual('&lt;script&gt;alert(&quot;Boom!&quot;);&lt;/script&gt;');
@@ -817,27 +810,29 @@ describe('Notes', function() {
   });
 
   describe('hasQuickActions', () => {
+    let notes;
+
     beforeEach(() => {
-      this.notes = new Notes('', []);
+      notes = new Notes('', []);
     });
 
     it('should return true when comment begins with a quick action', () => {
       const sampleComment = '/wip\n/milestone %1.0\n/merge\n/unassign Merging this';
-      const hasQuickActions = this.notes.hasQuickActions(sampleComment);
+      const hasQuickActions = notes.hasQuickActions(sampleComment);
 
       expect(hasQuickActions).toBeTruthy();
     });
 
     it('should return false when comment does NOT begin with a quick action', () => {
       const sampleComment = 'Hey, /unassign Merging this';
-      const hasQuickActions = this.notes.hasQuickActions(sampleComment);
+      const hasQuickActions = notes.hasQuickActions(sampleComment);
 
       expect(hasQuickActions).toBeFalsy();
     });
 
     it('should return false when comment does NOT have any quick actions', () => {
       const sampleComment = 'Looking good, Awesome!';
-      const hasQuickActions = this.notes.hasQuickActions(sampleComment);
+      const hasQuickActions = notes.hasQuickActions(sampleComment);
 
       expect(hasQuickActions).toBeFalsy();
     });
@@ -845,25 +840,25 @@ describe('Notes', function() {
 
   describe('stripQuickActions', () => {
     it('should strip quick actions from the comment which begins with a quick action', () => {
-      this.notes = new Notes();
+      const notes = new Notes();
       const sampleComment = '/wip\n/milestone %1.0\n/merge\n/unassign Merging this';
-      const stripedComment = this.notes.stripQuickActions(sampleComment);
+      const stripedComment = notes.stripQuickActions(sampleComment);
 
       expect(stripedComment).toBe('');
     });
 
     it('should strip quick actions from the comment but leaves plain comment if it is present', () => {
-      this.notes = new Notes();
+      const notes = new Notes();
       const sampleComment = '/wip\n/milestone %1.0\n/merge\n/unassign\nMerging this';
-      const stripedComment = this.notes.stripQuickActions(sampleComment);
+      const stripedComment = notes.stripQuickActions(sampleComment);
 
       expect(stripedComment).toBe('Merging this');
     });
 
     it('should NOT strip string that has slashes within', () => {
-      this.notes = new Notes();
+      const notes = new Notes();
       const sampleComment = 'http://127.0.0.1:3000/root/gitlab-shell/issues/1';
-      const stripedComment = this.notes.stripQuickActions(sampleComment);
+      const stripedComment = notes.stripQuickActions(sampleComment);
 
       expect(stripedComment).toBe(sampleComment);
     });
@@ -875,15 +870,16 @@ describe('Notes', function() {
       { name: 'title', description: 'Change title', params: [{}] },
       { name: 'estimate', description: 'Set time estimate', params: [{}] },
     ];
+    let notes;
 
     beforeEach(() => {
-      this.notes = new Notes();
+      notes = new Notes();
     });
 
     it('should return executing quick action description when note has single quick action', () => {
       const sampleComment = '/close';
 
-      expect(this.notes.getQuickActionDescription(sampleComment, availableQuickActions)).toBe(
+      expect(notes.getQuickActionDescription(sampleComment, availableQuickActions)).toBe(
         'Applying command to close this issue',
       );
     });
@@ -891,7 +887,7 @@ describe('Notes', function() {
     it('should return generic multiple quick action description when note has multiple quick actions', () => {
       const sampleComment = '/close\n/title [Duplicate] Issue foobar';
 
-      expect(this.notes.getQuickActionDescription(sampleComment, availableQuickActions)).toBe(
+      expect(notes.getQuickActionDescription(sampleComment, availableQuickActions)).toBe(
         'Applying multiple commands',
       );
     });
@@ -899,7 +895,7 @@ describe('Notes', function() {
     it('should return generic quick action description when available quick actions list is not populated', () => {
       const sampleComment = '/close\n/title [Duplicate] Issue foobar';
 
-      expect(this.notes.getQuickActionDescription(sampleComment)).toBe('Applying command');
+      expect(notes.getQuickActionDescription(sampleComment)).toBe('Applying command');
     });
   });
 
@@ -909,13 +905,14 @@ describe('Notes', function() {
     const currentUsername = 'root';
     const currentUserFullname = 'Administrator';
     const currentUserAvatar = 'avatar_url';
+    let notes;
 
     beforeEach(() => {
-      this.notes = new Notes('', []);
+      notes = new Notes('', []);
     });
 
     it('should return constructed placeholder element for regular note based on form contents', () => {
-      const $tempNote = this.notes.createPlaceholderNote({
+      const $tempNote = notes.createPlaceholderNote({
         formContent: sampleComment,
         uniqueId,
         isDiscussionNote: false,
@@ -929,8 +926,8 @@ describe('Notes', function() {
       expect($tempNote.attr('id')).toEqual(uniqueId);
       expect($tempNote.hasClass('being-posted')).toBeTruthy();
       expect($tempNote.hasClass('fade-in-half')).toBeTruthy();
-      $tempNote.find('.timeline-icon > a, .note-header-info > a').each(function() {
-        expect($(this).attr('href')).toEqual(`/${currentUsername}`);
+      $tempNote.find('.timeline-icon > a, .note-header-info > a').each((i, el) => {
+        expect(el.getAttribute('href')).toEqual(`/${currentUsername}`);
       });
 
       expect($tempNote.find('.timeline-icon .avatar').attr('src')).toEqual(currentUserAvatar);
@@ -958,7 +955,7 @@ describe('Notes', function() {
     });
 
     it('should return constructed placeholder element for discussion note based on form contents', () => {
-      const $tempNote = this.notes.createPlaceholderNote({
+      const $tempNote = notes.createPlaceholderNote({
         formContent: sampleComment,
         uniqueId,
         isDiscussionNote: true,
@@ -972,7 +969,7 @@ describe('Notes', function() {
 
     it('should return a escaped user name', () => {
       const currentUserFullnameXSS = 'Foo <script>alert("XSS")</script>';
-      const $tempNote = this.notes.createPlaceholderNote({
+      const $tempNote = notes.createPlaceholderNote({
         formContent: sampleComment,
         uniqueId,
         isDiscussionNote: false,
@@ -994,14 +991,15 @@ describe('Notes', function() {
   describe('createPlaceholderSystemNote', () => {
     const sampleCommandDescription = 'Applying command to close this issue';
     const uniqueId = 'b1234-a4567';
+    let notes;
 
     beforeEach(() => {
-      this.notes = new Notes('', []);
-      spyOn(_, 'escape').and.callFake(htmlEscape);
+      notes = new Notes('', []);
+      jest.spyOn(_, 'escape');
     });
 
     it('should return constructed placeholder element for system note based on form contents', () => {
-      const $tempNote = this.notes.createPlaceholderSystemNote({
+      const $tempNote = notes.createPlaceholderSystemNote({
         formContent: sampleCommandDescription,
         uniqueId,
       });
@@ -1020,29 +1018,28 @@ describe('Notes', function() {
   });
 
   describe('appendFlash', () => {
-    beforeEach(() => {
-      this.notes = new Notes();
-    });
-
     it('shows a flash message', () => {
-      this.notes.addFlash('Error message', FLASH_TYPE_ALERT, this.notes.parentTimeline.get(0));
+      const notes = new Notes('', []);
+      notes.addFlash('Error message', FLASH_TYPE_ALERT, notes.parentTimeline.get(0));
 
-      expect($('.flash-alert').is(':visible')).toBeTruthy();
+      const flash = $('.flash-alert')[0];
+      expect(document.contains(flash)).toBe(true);
+      expect(flash.parentNode.style.display).toBe('block');
     });
   });
 
   describe('clearFlash', () => {
     beforeEach(() => {
       $(document).off('ajax:success');
-      this.notes = new Notes();
     });
 
     it('hides visible flash message', () => {
-      this.notes.addFlash('Error message 1', FLASH_TYPE_ALERT, this.notes.parentTimeline.get(0));
-
-      this.notes.clearFlash();
-
-      expect($('.flash-alert').is(':visible')).toBeFalsy();
+      const notes = new Notes('', []);
+      notes.addFlash('Error message 1', FLASH_TYPE_ALERT, notes.parentTimeline.get(0));
+      const flash = $('.flash-alert')[0];
+      notes.clearFlash();
+      expect(flash.parentNode.style.display).toBe('none');
+      expect(notes.flashContainer).toBeNull();
     });
   });
 });