Add monkey patch to ensure global ajaxSend listener is cleaned up.

index.js

@@ -4,6 +4,10 @@
 module.exports = {
   name: 'ember-test-helpers',
 
+  included() {
+    this.import('vendor/monkey-patches.js', { type: 'test' });
+  },
+
   treeForAddonTestSupport(tree) {
     // intentionally not calling _super here
     // so that can have our `import`'s be

vendor/monkey-patches.js

@@ -0,0 +1,35 @@
+/* globals require, Ember, jQuery */
+
+(function() {
+  if (typeof jQuery !== 'undefined') {
+    var _Ember;
+    if (typeof Ember !== 'undefined') {
+      _Ember = Ember;
+    } else {
+      _Ember = require('ember').default;
+    }
+
+    var pendingRequests;
+    if (Ember.__loader.registry['ember-testing/test/pending_requests']) {
+      pendingRequests = Ember.__loader.require('ember-testing/test/pending_requests');
+    }
+
+    if (pendingRequests) {
+      // This exists to ensure that the AJAX listeners setup by Ember itself
+      // (which as of 2.17 are not properly torn down) get cleared and released
+      // when the application is destroyed. Without this, any AJAX requests
+      // that happen _between_ when acceptance tests will always share
+      // `pendingRequests`.
+      _Ember.Application.reopen({
+        willDestroy() {
+          jQuery(document).off('ajaxSend', pendingRequests.incrementPendingRequests);
+          jQuery(document).off('ajaxComplete', pendingRequests.decrementPendingRequests);
+
+          pendingRequests.clearPendingRequests();
+
+          this._super.apply(this, arguments);
+        },
+      });
+    }
+  }
+})();