[Fiber] Mock ReactDOM for Fiber Tests

scripts/jest/environment.js

@@ -1,2 +1,11 @@
 /* eslint-disable */
 global.__DEV__ = true;
+
+// For testing DOM Fiber, we synchronously invoke all the scheduling.
+global.requestAnimationFrame = function(callback) {
+  callback();
+};
+
+global.requestIdleCallback = function(callback) {
+  callback({ timeRemaining() { return Infinity; } });
+};

scripts/jest/test-framework-setup.js

@@ -1,5 +1,9 @@
 'use strict';
 
+// We want to globally mock this but jest doesn't let us do that by default
+// for a file that already exists. So we have to explicitly mock it.
+jest.mock('ReactDOM');
+
 var env = jasmine.getEnv();
 
 var callCount = 0;

src/renderers/dom/__mocks__/ReactDOM.js

@@ -0,0 +1,17 @@
+/**
+ * Copyright 2013-2015, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+'use strict';
+
+var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
+
+var useFiber = ReactDOMFeatureFlags.useFiber;
+
+module.exports =
+  useFiber ? require('ReactDOMFiber') : require.requireActual('ReactDOM');

src/renderers/dom/shared/ReactDOMFeatureFlags.js

@@ -13,6 +13,7 @@
 
 var ReactDOMFeatureFlags = {
   useCreateElement: true,
+  useFiber: false,
 };
 
 module.exports = ReactDOMFeatureFlags;