Bring back OSS testing builds

We removed this in #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
- adds a testing build for react as well
- and finally removes the testing sigils from prod builds. nice.
- misc test config changes

Author: threepointone

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-devtools-shared/src/__tests__/legacy/inspectElement-test.js

@@ -12,6 +12,10 @@ import type {DehydratedData} from 'react-devtools-shared/src/devtools/views/Comp
 import type {FrontendBridge} from 'react-devtools-shared/src/bridge';
 import type Store from 'react-devtools-shared/src/devtools/store';
 
+// unmock the testing builds
+jest.unmock('react');
+jest.unmock('react-dom');
+
 describe('InspectedElementContext', () => {
   let React;
   let ReactDOM;

packages/react-devtools-shared/src/__tests__/legacy/storeLegacy-v15-test.js

@@ -7,6 +7,10 @@
  * @flow
  */
 
+// unmock the testing builds
+jest.unmock('react');
+jest.unmock('react-dom');
+
 describe('Store (legacy)', () => {
   let React;
   let ReactDOM;

packages/react-dom/npm/testing.js

@@ -0,0 +1,7 @@
+'use strict';
+
+if (process.env.NODE_ENV === 'production') {
+  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/npm/unstable-testing.js

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

packages/react-dom/package.json

@@ -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(() => {});