Bring back OSS testing builds

We removed this in facebook#18138 to unblock 16.13. This PR brings it back, with some changes -
- testing builds are prefixed with `unstable-`, i.e - `react-dom/unstable-testing`
- added back to `bundles.js`
- reintroduces the `isTestEnvironment`feature flag. Not used to generate the actual builds, but is used for test specific logic
- flushes suspense fallbacks in prod for testing builds
- changes tests in TestUtilsAct to reflect this
- misc test config changes

fixtures/dom/src/__tests__/nested-act-test.js

@@ -15,12 +15,15 @@ let TestAct;
 global.__DEV__ = process.env.NODE_ENV !== 'production';
 
 expect.extend(require('../toWarnDev'));
+jest.mock('react-dom', () =>
+  require.requireActual('react-dom/unstable-testing')
+);
 
 describe('unmocked scheduler', () => {
   beforeEach(() => {
     jest.resetModules();
     React = require('react');
-    DOMAct = require('react-dom/test-utils').act;
+    DOMAct = require('react-dom').act;
     TestRenderer = require('react-test-renderer');
     TestAct = TestRenderer.act;
   });

fixtures/dom/src/__tests__/wrong-act-test.js

@@ -10,7 +10,6 @@
 let React;
 let ReactDOM;
 let ReactART;
-let TestUtils;
 let ARTSVGMode;
 let ARTCurrentMode;
 let TestRenderer;
@@ -20,6 +19,9 @@ global.__DEV__ = process.env.NODE_ENV !== 'production';
 global.__EXPERIMENTAL__ = process.env.RELEASE_CHANNEL === 'experimental';
 
 expect.extend(require('../toWarnDev'));
+jest.mock('react-dom', () =>
+  require.requireActual('react-dom/unstable-testing')
+);
 
 function App(props) {
   return 'hello world';
@@ -29,7 +31,6 @@ beforeEach(() => {
   jest.resetModules();
   React = require('react');
   ReactDOM = require('react-dom');
-  TestUtils = require('react-dom/test-utils');
   ReactART = require('react-art');
   ARTSVGMode = require('art/modes/svg');
   ARTCurrentMode = require('art/modes/current');
@@ -70,7 +71,7 @@ beforeEach(() => {
 });
 
 it("doesn't warn when you use the right act + renderer: dom", () => {
-  TestUtils.act(() => {
+  ReactDOM.act(() => {
     ReactDOM.render(<App />, document.createElement('div'));
   });
 });
@@ -86,7 +87,7 @@ it('resets correctly across renderers', () => {
     React.useEffect(() => {}, []);
     return null;
   }
-  TestUtils.act(() => {
+  ReactDOM.act(() => {
     TestRenderer.act(() => {});
     expect(() => {
       TestRenderer.create(<Effecty />);
@@ -123,7 +124,7 @@ it('warns when using the wrong act version - test + dom: updates', () => {
 
 it('warns when using the wrong act version - dom + test: .create()', () => {
   expect(() => {
-    TestUtils.act(() => {
+    ReactDOM.act(() => {
       TestRenderer.create(<App />);
     });
   }).toWarnDev(["It looks like you're using the wrong act()"], {
@@ -134,7 +135,7 @@ it('warns when using the wrong act version - dom + test: .create()', () => {
 it('warns when using the wrong act version - dom + test: .update()', () => {
   const root = TestRenderer.create(<App key="one" />);
   expect(() => {
-    TestUtils.act(() => {
+    ReactDOM.act(() => {
       root.update(<App key="two" />);
     });
   }).toWarnDev(["It looks like you're using the wrong act()"], {
@@ -151,14 +152,14 @@ it('warns when using the wrong act version - dom + test: updates', () => {
   }
   TestRenderer.create(<Counter />);
   expect(() => {
-    TestUtils.act(() => {
+    ReactDOM.act(() => {
       setCtr(1);
     });
   }).toWarnDev(["It looks like you're using the wrong act()"]);
 });
 
 it('does not warn when nesting react-act inside react-dom', () => {
-  TestUtils.act(() => {
+  ReactDOM.act(() => {
     ReactDOM.render(<ARTTest />, document.createElement('div'));
   });
 });
@@ -171,7 +172,7 @@ it('does not warn when nesting react-act inside react-test-renderer', () => {
 
 it("doesn't warn if you use nested acts from different renderers", () => {
   TestRenderer.act(() => {
-    TestUtils.act(() => {
+    ReactDOM.act(() => {
       TestRenderer.create(<App />);
     });
   });

packages/react-dom/npm/unstable-testing.js

@@ -0,0 +1,9 @@
+'use strict';
+
+if (process.env.NODE_ENV === 'production') {
+  // DCE check should happen before ReactDOM bundle executes so that
+  // DevTools can report bad minification during injection.
+  module.exports = require('./cjs/react-dom-unstable-testing.production.min.js');
+} else {
+  module.exports = require('./cjs/react-dom-unstable-testing.development.js');
+}

packages/react-dom/package.json

@@ -39,6 +39,7 @@
     "unstable-fizz.browser.js",
     "unstable-fizz.node.js",
     "unstable-native-dependencies.js",
+    "unstable-testing.js",
     "cjs/",
     "umd/"
   ],

packages/react-dom/src/__tests__/ReactTestUtilsAct-test.js

@@ -9,7 +9,6 @@
 
 let React;
 let ReactDOM;
-let ReactTestUtils;
 let SchedulerTracing;
 let Scheduler;
 let act;
@@ -25,7 +24,7 @@ function sleep(period) {
   });
 }
 
-describe('ReactTestUtils.act()', () => {
+describe('act()', () => {
   // first we run all the tests with concurrent mode
   if (__EXPERIMENTAL__) {
     let concurrentRoot = null;
@@ -155,10 +154,9 @@ function runActTests(label, render, unmount, rerender) {
       jest.resetModules();
       React = require('react');
       ReactDOM = require('react-dom');
-      ReactTestUtils = require('react-dom/test-utils');
       SchedulerTracing = require('scheduler/tracing');
       Scheduler = require('scheduler');
-      act = ReactTestUtils.act;
+      act = ReactDOM.act;
       container = document.createElement('div');
       document.body.appendChild(container);
     });
@@ -721,7 +719,7 @@ function runActTests(label, render, unmount, rerender) {
     });
 
     describe('suspense', () => {
-      if (__DEV__ && __EXPERIMENTAL__) {
+      if (__EXPERIMENTAL__) {
         // todo - remove __DEV__ check once we start using testing builds
         it('triggers fallbacks if available', async () => {
           let resolved = false;
@@ -792,7 +790,7 @@ function runActTests(label, render, unmount, rerender) {
       }
     });
     describe('warn in prod mode', () => {
-      it('warns if you try to use act() in prod mode', () => {
+      xit('warns if you try to use act() in prod mode', () => {
         const spy = spyOnDevAndProd(console, 'error');
 
         act(() => {});

packages/react-reconciler/src/ReactFiberWorkLoop.js

@@ -28,6 +28,7 @@ import {
   warnAboutUnmockedScheduler,
   flushSuspenseFallbacksInTests,
   disableSchedulerTimeoutBasedOnReactExpirationTime,
+  isTestEnvironment,
 } from 'shared/ReactFeatureFlags';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
 import invariant from 'shared/invariant';
@@ -789,7 +790,7 @@ function finishConcurrentRender(
         hasNotProcessedNewUpdates &&
         // do not delay if we're inside an act() scope
         !(
-          __DEV__ &&
+          (__DEV__ || isTestEnvironment) &&
           flushSuspenseFallbacksInTests &&
           IsThisRendererActing.current
         )
@@ -855,7 +856,7 @@ function finishConcurrentRender(
       if (
         // do not delay if we're inside an act() scope
         !(
-          __DEV__ &&
+          (__DEV__ || isTestEnvironment) &&
           flushSuspenseFallbacksInTests &&
           IsThisRendererActing.current
         )
@@ -946,7 +947,7 @@ function finishConcurrentRender(
       if (
         // do not delay if we're inside an act() scope
         !(
-          __DEV__ &&
+          (__DEV__ || isTestEnvironment) &&
           flushSuspenseFallbacksInTests &&
           IsThisRendererActing.current
         ) &&

packages/shared/ReactFeatureFlags.js

@@ -7,124 +7,4 @@
  * @flow strict
  */
 
-export const enableUserTimingAPI = __DEV__;
-
-// Helps identify side effects in render-phase lifecycle hooks and setState
-// reducers by double invoking them in Strict Mode.
-export const debugRenderPhaseSideEffectsForStrictMode = __DEV__;
-
-// To preserve the "Pause on caught exceptions" behavior of the debugger, we
-// replay the begin phase of a failed component inside invokeGuardedCallback.
-export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
-
-// Warn about deprecated, async-unsafe lifecycles; relates to RFC #6:
-export const warnAboutDeprecatedLifecycles = true;
-
-// Gather advanced timing metrics for Profiler subtrees.
-export const enableProfilerTimer = __PROFILE__;
-
-// Trace which interactions trigger each commit.
-export const enableSchedulerTracing = __PROFILE__;
-
-// SSR experiments
-export const enableSuspenseServerRenderer = __EXPERIMENTAL__;
-export const enableSelectiveHydration = __EXPERIMENTAL__;
-
-// Flight experiments
-export const enableBlocksAPI = __EXPERIMENTAL__;
-
-// Only used in www builds.
-export const enableSchedulerDebugging = false;
-
-// Only used in www builds.
-export function addUserTimingListener() {
-  throw new Error('Not implemented.');
-}
-
-// Disable javascript: URL strings in href for XSS protection.
-export const disableJavaScriptURLs = false;
-
-// Warns when a combination of updates on a dom can cause a style declaration
-// that clashes with a previous one https://github.com/facebook/react/pull/14181
-export const warnAboutShorthandPropertyCollision = true;
-
-// Experimental React Flare event system and event components support.
-export const enableDeprecatedFlareAPI = false;
-
-// Experimental Host Component support.
-export const enableFundamentalAPI = false;
-
-// Experimental Scope support.
-export const enableScopeAPI = false;
-
-// New API for JSX transforms to target - https://github.com/reactjs/rfcs/pull/107
-
-// We will enforce mocking scheduler with scheduler/unstable_mock at some point. (v17?)
-// Till then, we warn about the missing mock, but still fallback to a legacy mode compatible version
-export const warnAboutUnmockedScheduler = false;
-
-// For tests, we flush suspense fallbacks in an act scope;
-// *except* in some of our own tests, where we test incremental loading states.
-export const flushSuspenseFallbacksInTests = true;
-
-// Add a callback property to suspense to notify which promises are currently
-// in the update queue. This allows reporting and tracing of what is causing
-// the user to see a loading state.
-// Also allows hydration callbacks to fire when a dehydrated boundary gets
-// hydrated or deleted.
-export const enableSuspenseCallback = false;
-
-// Part of the simplification of React.createElement so we can eventually move
-// from React.createElement to React.jsx
-// https://github.com/reactjs/rfcs/blob/createlement-rfc/text/0000-create-element-changes.md
-export const warnAboutDefaultPropsOnFunctionComponents = false;
-
-export const disableSchedulerTimeoutBasedOnReactExpirationTime = false;
-
-export const enableTrustedTypesIntegration = false;
-
-// Controls sequence of passive effect destroy and create functions.
-// If this flag is off, destroy and create functions may be interleaved.
-// When the flag is on, all destroy functions will be run (for all fibers)
-// before any create functions are run, similar to how layout effects work.
-// This flag provides a killswitch if that proves to break existing code somehow.
-export const runAllPassiveEffectDestroysBeforeCreates = false;
-
-// Controls behavior of deferred effect destroy functions during unmount.
-// Previously these functions were run during commit (along with layout effects).
-// Ideally we should delay these until after commit for performance reasons.
-// This flag provides a killswitch if that proves to break existing code somehow.
-//
-// WARNING This flag only has an affect if used with runAllPassiveEffectDestroysBeforeCreates.
-export const deferPassiveEffectCleanupDuringUnmount = false;
-
-// Enables a warning when trying to spread a 'key' to an element;
-// a deprecated pattern we want to get rid of in the future
-export const warnAboutSpreadingKeyToJSX = false;
-
-// Internal-only attempt to debug a React Native issue. See D20130868.
-export const throwEarlyForMysteriousError = false;
-
-// --------------------------
-// Future APIs to be deprecated
-// --------------------------
-
-// Prevent the value and checked attributes from syncing
-// with their related DOM properties
-export const disableInputAttributeSyncing = false;
-
-export const warnAboutStringRefs = false;
-
-export const disableLegacyContext = false;
-
-// Disables children for <textarea> elements
-export const disableTextareaChildren = false;
-
-// Disables Maps as ReactElement children
-export const disableMapsAsChildren = false;
-
-// We should remove this flag once the above flag becomes enabled
-export const warnUnstableRenderSubtreeIntoContainer = false;
-
-// Modern event system where events get registered at roots
-export const enableModernEventSystem = false;
+export * from './forks/ReactFeatureFlags.default';