Core: Fix IE 10 and IE 11 compatibility of internal Promise with sinon.useFakeTimers

The Promise polyfill needs to save the unmodified reference to the
`setImmediate` function in IE, for use in `Promise._immediateFn`.

This broke in QUnit 2.14.0, with the introduction of internal Promise usage
as part of #1535. 

Closes #1738.

Author: timmywil

lib/promise-polyfill.js

@@ -36,6 +36,8 @@ Patches for use in QUnit:
 
 - 2021-01-10: Add 'globalThis' to globalNS implementation to support SpiderMonkey.
 
+- 2024-02-07: Save unmodified setImmediate to avoid conflicts with Sinon fake timers.
+
 */
 
 (function () { 'use strict';
@@ -373,16 +375,18 @@ Promise.race = function(arr) {
 };
 
 // Use polyfill for setImmediate for performance gains
-Promise._immediateFn =
+// @ts-ignore
+if (typeof setImmediate === 'function') {
   // @ts-ignore
-  (typeof setImmediate === 'function' &&
-    function(fn) {
-      // @ts-ignore
-      setImmediate(fn);
-    }) ||
-  function(fn) {
+  var setImmediateFunc = setImmediate;
+  Promise._immediateFn = function(fn) {
+    setImmediateFunc(fn);
+  };
+} else {
+  Promise._immediateFn = function(fn) {
     setTimeoutFunc(fn, 0);
   };
+}
 
 Promise._unhandledRejectionFn = function _unhandledRejectionFn(err) {
   if (typeof console !== 'undefined' && console) {

test/main/promise.js

@@ -8,6 +8,27 @@ var defer = typeof setTimeout !== 'undefined'
     Promise.resolve().then(fn);
   };
 
+// Get the global namespace the same way as the Promise polyfill.
+var globalNS = (function () {
+  if (typeof globalThis !== 'undefined') {
+    // eslint-disable-next-line no-undef
+    return globalThis;
+  }
+  if (typeof self !== 'undefined') {
+    // eslint-disable-next-line no-undef
+    return self;
+  }
+  if (typeof window !== 'undefined') {
+    // eslint-disable-next-line no-undef
+    return window;
+  }
+  if (typeof global !== 'undefined') {
+    // eslint-disable-next-line no-undef
+    return global;
+  }
+  throw new Error('unable to locate global object');
+})();
+
 // NOTE: Adds 1 assertion
 function createMockPromise (assert, reject, value) {
   if (arguments.length < 3) {
@@ -247,4 +268,29 @@ QUnit.module('Support for Promise', function () {
 
     return createMockPromise(assert, true, new Error('this is an error'));
   });
+
+  QUnit.module('compatible with fake timers', {
+    beforeEach: function (assert) {
+      this.setTimeout = globalNS.setTimeout;
+      globalNS.setTimeout = function () {};
+      if (globalNS.setImmediate) {
+        this.setImmediate = globalNS.setImmediate;
+        globalNS.setImmediate = function () {};
+      }
+      // Adds 1 assertion
+      return createMockPromise(assert);
+    },
+    afterEach: function (assert) {
+      globalNS.setTimeout = this.setTimeout;
+      if (this.setImmediate) {
+        globalNS.setImmediate = this.setImmediate;
+      }
+      // Adds 1 assertion
+      return createMockPromise(assert);
+    }
+  });
+
+  QUnit.test('test', function (assert) {
+    assert.expect(2);
+  });
 });