[BUGFIX beta] revert jquery-less pendingRequest event handling

In general,Ember's testing system leverages `ajaxSend` and
`ajaxComplete` events to know when `jQuery.ajax` requests are pending
(and it should therefore "pause settledness" of the testing helpers like
`click` / `andThen` / etc).

In the Ember 3.1 cycle Ember changed from using `jQuery.on` to
`document.addEventListener` to subscribe to these events. Unfortunately,
`jQuery.ajax` **does not** trigger listeners added in this way (we would
have had to do `document.onajaxSend = function() { /* stuff here */ }`).
The result of this change is that "normal" acceptance testing helpers
will _no longer_ be able to detect and wait for pending `jQuery.ajax`.

So, for example, you might expect that given the following

```js
await click('#some-selector');

assert.equal(
   $('#something-that-should-exist-after-an-ajax-call').text(),
   'hi'
);
```

the click helper would wait until `jQuery.ajax` calls were settled
before the assertion, but prior to the changes in this commit
the promise returned by `click` would **not** wait until the
`jQuery.ajax` request was completed and therefore the assertion would
fail.

---

This commit reverts the changes to use `document.addEventListener` back
to using `jQuery.on` directly when `jQuery` is available.

Many bothans died to bring us this information. 😭 😢 :crying_cat:

Paired with @rwjblue to resolve this issue.

packages/ember-testing/lib/setup_for_testing.js

@@ -1,6 +1,7 @@
 /* global self */
 
 import { setTesting } from 'ember-debug';
+import { jQuery } from 'ember-views';
 import { getAdapter, setAdapter } from './test/adapter';
 import {
   incrementPendingRequests,
@@ -9,9 +10,7 @@ import {
 } from './test/pending_requests';
 import Adapter from './adapters/adapter';
 import QUnitAdapter from './adapters/qunit';
-/**
-@module ember
-*/
+
 /**
   Sets Ember up for testing. This is useful to perform
   basic setup steps in order to unit test.
@@ -33,11 +32,13 @@ export default function setupForTesting() {
     setAdapter(typeof self.QUnit === 'undefined' ? new Adapter() : new QUnitAdapter());
   }
 
-  document.removeEventListener('ajaxSend', incrementPendingRequests);
-  document.removeEventListener('ajaxComplete', decrementPendingRequests);
+  if (jQuery) {
+    jQuery(document).off('ajaxSend', incrementPendingRequests);
+    jQuery(document).off('ajaxComplete', decrementPendingRequests);
 
-  clearPendingRequests();
+    clearPendingRequests();
 
-  document.addEventListener('ajaxSend', incrementPendingRequests);
-  document.addEventListener('ajaxComplete', decrementPendingRequests);
+    jQuery(document).on('ajaxSend', incrementPendingRequests);
+    jQuery(document).on('ajaxComplete', decrementPendingRequests);
+  }
 }

packages/ember-testing/lib/test/pending_requests.js

@@ -8,13 +8,11 @@ export function clearPendingRequests() {
   requests.length = 0;
 }
 
-export function incrementPendingRequests({ detail } = { detail: { xhr: null } }) {
-  let xhr = detail.xhr;
+export function incrementPendingRequests(_, xhr) {
   requests.push(xhr);
 }
 
-export function decrementPendingRequests({ detail } = { detail: { xhr: null } }) {
-  let xhr = detail.xhr;
+export function decrementPendingRequests(_, xhr) {
   for (let i = 0; i < requests.length; i++) {
     if (xhr === requests[i]) {
       requests.splice(i, 1);

packages/ember-testing/tests/helpers_test.js

@@ -4,7 +4,7 @@ import { Route } from 'ember-routing';
 import { Controller, RSVP } from 'ember-runtime';
 import { later } from 'ember-metal';
 import { Component } from 'ember-glimmer';
-import { jQueryDisabled } from 'ember-views';
+import { jQueryDisabled, jQuery } from 'ember-views';
 
 import Test from '../test';
 import setupForTesting from '../setup_for_testing';
@@ -26,12 +26,6 @@ function registerHelper() {
   Test.registerHelper('LeakyMcLeakLeak', () => {});
 }
 
-function customEvent(name, xhr) {
-  let event = document.createEvent('CustomEvent');
-  event.initCustomEvent(name, true, true, { xhr });
-  document.dispatchEvent(event);
-}
-
 function assertHelpers(assert, application, helperContainer, expected) {
   if (!helperContainer) {
     helperContainer = window;
@@ -1040,15 +1034,19 @@ if (!jQueryDisabled) {
   moduleFor(
     'ember-testing: pendingRequests',
     class extends HelpersApplicationTestCase {
+      trigger(type, xhr) {
+        jQuery(document).trigger(type, xhr);
+      }
+
       [`@test pendingRequests is maintained for ajaxSend and ajaxComplete events`](assert) {
         assert.equal(pendingRequests(), 0);
 
         let xhr = { some: 'xhr' };
 
-        customEvent('ajaxSend', xhr);
+        this.trigger('ajaxSend', xhr);
         assert.equal(pendingRequests(), 1, 'Ember.Test.pendingRequests was incremented');
 
-        customEvent('ajaxComplete', xhr);
+        this.trigger('ajaxComplete', xhr);
         assert.equal(pendingRequests(), 0, 'Ember.Test.pendingRequests was decremented');
       }
 
@@ -1059,7 +1057,7 @@ if (!jQueryDisabled) {
 
         let xhr = { some: 'xhr' };
 
-        customEvent('ajaxSend', xhr);
+        this.trigger('ajaxSend', xhr);
         assert.equal(pendingRequests(), 1, 'Ember.Test.pendingRequests was incremented');
 
         setupForTesting();
@@ -1068,10 +1066,10 @@ if (!jQueryDisabled) {
 
         let altXhr = { some: 'more xhr' };
 
-        customEvent('ajaxSend', altXhr);
+        this.trigger('ajaxSend', altXhr);
         assert.equal(pendingRequests(), 1, 'Ember.Test.pendingRequests was incremented');
 
-        customEvent('ajaxComplete', xhr);
+        this.trigger('ajaxComplete', xhr);
         assert.equal(
           pendingRequests(),
           1,