Fixed scheduler setTimeout fallback (#14358)

* Fixed scheduler setTimeout fallback
* Moved unit-test-specific setTimeout code into a new NPM package, jest-mock-scheduler.

packages/jest-mock-scheduler/README.md

@@ -0,0 +1,5 @@
+# `jest-mock-scheduler`
+
+Jest matchers and utilities for testing the `scheduler` package.
+
+This package is experimental. APIs may change between releases.

packages/jest-mock-scheduler/index.js

@@ -0,0 +1,8 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+export * from './src/JestMockScheduler';

packages/jest-mock-scheduler/npm/index.js

@@ -0,0 +1,7 @@
+'use strict';
+
+if (process.env.NODE_ENV === 'production') {
+  module.exports = require('./cjs/jest-mock-scheduler.production.min.js');
+} else {
+  module.exports = require('./cjs/jest-mock-scheduler.development.js');
+}

packages/jest-mock-scheduler/package.json

@@ -0,0 +1,28 @@
+{
+  "name": "jest-mock-scheduler",
+  "private": true,
+  "version": "0.1.0",
+  "description": "Jest matchers and utilities for testing the scheduler package.",
+  "main": "index.js",
+  "repository": "facebook/react",
+  "keywords": [
+    "jest",
+    "scheduler"
+  ],
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/facebook/react/issues"
+  },
+  "homepage": "https://reactjs.org/",
+  "peerDependencies": {
+    "jest": "^23.0.1",
+    "scheduler": "^0.11.0"
+  },
+  "files": [
+    "LICENSE",
+    "README.md",
+    "build-info.json",
+    "index.js",
+    "cjs/"
+  ]
+}

packages/jest-mock-scheduler/src/JestMockScheduler.js

@@ -0,0 +1,61 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// Max 31 bit integer. The max integer size in V8 for 32-bit systems.
+// Math.pow(2, 30) - 1
+// 0b111111111111111111111111111111
+const maxSigned31BitInt = 1073741823;
+
+export function mockRestore() {
+  delete global._schedMock;
+}
+
+let callback = null;
+let currentTime = -1;
+
+function flushCallback(didTimeout, ms) {
+  if (callback !== null) {
+    let cb = callback;
+    callback = null;
+    try {
+      currentTime = ms;
+      cb(didTimeout);
+    } finally {
+      currentTime = -1;
+    }
+  }
+}
+
+function requestHostCallback(cb, ms) {
+  if (currentTime !== -1) {
+    // Protect against re-entrancy.
+    setTimeout(requestHostCallback, 0, cb, ms);
+  } else {
+    callback = cb;
+    setTimeout(flushCallback, ms, true, ms);
+    setTimeout(flushCallback, maxSigned31BitInt, false, maxSigned31BitInt);
+  }
+}
+
+function cancelHostCallback() {
+  callback = null;
+}
+
+function shouldYieldToHost() {
+  return false;
+}
+
+function getCurrentTime() {
+  return currentTime === -1 ? 0 : currentTime;
+}
+
+global._schedMock = [
+  requestHostCallback,
+  cancelHostCallback,
+  shouldYieldToHost,
+  getCurrentTime,
+];

packages/scheduler/src/Scheduler.js

@@ -447,12 +447,20 @@ var requestHostCallback;
 var cancelHostCallback;
 var shouldYieldToHost;
 
-if (typeof window !== 'undefined' && window._schedMock) {
+var globalValue = null;
+if (typeof window !== 'undefined') {
+  globalValue = window;
+} else if (typeof global !== 'undefined') {
+  globalValue = global;
+}
+
+if (globalValue && globalValue._schedMock) {
   // Dynamic injection, only for testing purposes.
-  var impl = window._schedMock;
-  requestHostCallback = impl[0];
-  cancelHostCallback = impl[1];
-  shouldYieldToHost = impl[2];
+  var globalImpl = globalValue._schedMock;
+  requestHostCallback = globalImpl[0];
+  cancelHostCallback = globalImpl[1];
+  shouldYieldToHost = globalImpl[2];
+  getCurrentTime = globalImpl[3];
 } else if (
   // If Scheduler runs in a non-DOM environment, it falls back to a naive
   // implementation using setTimeout.
@@ -460,28 +468,23 @@ if (typeof window !== 'undefined' && window._schedMock) {
   // Check if MessageChannel is supported, too.
   typeof MessageChannel !== 'function'
 ) {
+  // If this accidentally gets imported in a non-browser environment, e.g. JavaScriptCore,
+  // fallback to a naive implementation.
   var _callback = null;
-  var _currentTime = -1;
-  var _flushCallback = function(didTimeout, ms) {
+  var _flushCallback = function(didTimeout) {
     if (_callback !== null) {
       var cb = _callback;
       _callback = null;
-      try {
-        _currentTime = ms;
-        cb(didTimeout);
-      } finally {
-        _currentTime = -1;
-      }
+      cb(didTimeout);
     }
   };
   requestHostCallback = function(cb, ms) {
-    if (_currentTime !== -1) {
+    if (_callback !== null) {
       // Protect against re-entrancy.
-      setTimeout(requestHostCallback, 0, cb, ms);
+      setTimeout(requestHostCallback, 0, cb);
     } else {
       _callback = cb;
-      setTimeout(_flushCallback, ms, true, ms);
-      setTimeout(_flushCallback, maxSigned31BitInt, false, maxSigned31BitInt);
+      setTimeout(_flushCallback, 0, false);
     }
   };
   cancelHostCallback = function() {
@@ -490,9 +493,6 @@ if (typeof window !== 'undefined' && window._schedMock) {
   shouldYieldToHost = function() {
     return false;
   };
-  getCurrentTime = function() {
-    return _currentTime === -1 ? 0 : _currentTime;
-  };
 } else {
   if (typeof console !== 'undefined') {
     // TODO: Remove fb.me link

packages/scheduler/src/__tests__/Scheduler-test.js

@@ -30,6 +30,9 @@ describe('Scheduler', () => {
     jest.useFakeTimers();
     jest.resetModules();
 
+    const JestMockScheduler = require('jest-mock-scheduler');
+    JestMockScheduler.mockRestore();
+
     let _flushWork = null;
     let isFlushing = false;
     let timeoutID = -1;
@@ -123,16 +126,21 @@ describe('Scheduler', () => {
     function shouldYieldToHost() {
       return endOfFrame <= currentTime;
     }
+    function getCurrentTime() {
+      return currentTime;
+    }
 
     // Override host implementation
     delete global.performance;
     global.Date.now = () => {
       return currentTime;
     };
+
     window._schedMock = [
       requestHostCallback,
       cancelHostCallback,
       shouldYieldToHost,
+      getCurrentTime,
     ];
 
     const Schedule = require('scheduler');

packages/scheduler/src/__tests__/SchedulerDOM-test.js

@@ -88,6 +88,10 @@ describe('SchedulerDOM', () => {
       return currentTime;
     };
     jest.resetModules();
+
+    const JestMockScheduler = require('jest-mock-scheduler');
+    JestMockScheduler.mockRestore();
+
     Scheduler = require('scheduler');
   });
 

packages/shared/__tests__/ReactDOMFrameScheduling-test.js

@@ -22,6 +22,10 @@ describe('ReactDOMFrameScheduling', () => {
         };
       };
       jest.resetModules();
+
+      const JestMockScheduler = require('jest-mock-scheduler');
+      JestMockScheduler.mockRestore();
+
       spyOnDevAndProd(console, 'error');
       require('react-dom');
       expect(console.error.calls.count()).toEqual(1);

scripts/jest/setupTests.js

@@ -56,6 +56,8 @@ if (process.env.REACT_CLASS_EQUIVALENCE_TEST) {
     toMatchRenderedOutput: JestReact.unstable_toMatchRenderedOutput,
   });
 
+  require('jest-mock-scheduler');
+
   // We have a Babel transform that inserts guards against infinite loops.
   // If a loop runs for too many iterations, we throw an error and set this
   // global variable. The global lets us detect an infinite loop even if

scripts/rollup/bundles.js

@@ -462,6 +462,15 @@ const bundles = [
     externals: ['jest-diff'],
   },
 
+  /******* Jest Scheduler (experimental) *******/
+  {
+    bundleTypes: [NODE_DEV, NODE_PROD, FB_WWW_DEV, FB_WWW_PROD],
+    moduleType: ISOMORPHIC,
+    entry: 'jest-mock-scheduler',
+    global: 'JestMockScheduler',
+    externals: ['jest-diff'],
+  },
+
   /******* ESLint Plugin for Hooks (proposal) *******/
   {
     // TODO: it's awkward to create a bundle for this