act() - s / flushPassiveEffects / Scheduler.unstable_flushWithoutYi…

…elding (#15591)

* s/flushPassiveEffects/unstable_flushWithoutYielding

a first crack at flushing the scheduler manually from inside act(). uses unstable_flushWithoutYielding(). The tests that changed, mostly replaced toFlushAndYield(...) with toHaveYielded(). For some tests that tested the state of the tree before flushing effects (but still after updates), I replaced act() with bacthedUpdates().

* ugh lint

* pass build, flushPassiveEffects returns nothing now

* pass test-fire

* flush all work (not just effects), add a compatibility mode

of note, unstable_flushWithoutYielding now returns a boolean much like flushPassiveEffects

* umd build for scheduler/unstable_mock, pass the fixture with it

* add a comment to Shcduler.umd.js for why we're exporting unstable_flushWithoutYielding

* run testsutilsact tests in both sync/concurrent modes

* augh lint

* use a feature flag for the missing mock scheduler warning

I also tried writing a test for it, but couldn't get the scheduler to unmock. included the failing test.

* Update ReactTestUtilsAct-test.js

- pass the mock scheduler warning test,
- rewrite some tests to use Scheduler.yieldValue
- structure concurrent/legacy suites neatly

* pass failing tests in batchedmode-test

* fix pretty/lint/import errors

* pass test-build

* nit: pull .create(null) out of the act() call

fixtures/dom/.gitignore

@@ -8,6 +8,8 @@ coverage
 
 # production
 build
+public/scheduler-unstable_mock.development.js
+public/scheduler-unstable_mock.production.min.js
 public/react.development.js
 public/react.production.min.js
 public/react-dom.development.js

fixtures/dom/package.json

@@ -18,7 +18,7 @@
   },
   "scripts": {
     "start": "react-scripts start",
-    "prestart": "cp ../../build/node_modules/react/umd/react.development.js ../../build/node_modules/react-dom/umd/react-dom.development.js ../../build/node_modules/react/umd/react.production.min.js ../../build/node_modules/react-dom/umd/react-dom.production.min.js ../../build/node_modules/react-dom/umd/react-dom-server.browser.development.js ../../build/node_modules/react-dom/umd/react-dom-server.browser.production.min.js ../../build/node_modules/react-dom/umd/react-dom-test-utils.development.js ../../build/node_modules/react-dom/umd/react-dom-test-utils.production.min.js public/",
+    "prestart": "cp ../../build/node_modules/scheduler/umd/scheduler-unstable_mock.development.js ../../build/node_modules/scheduler/umd/scheduler-unstable_mock.production.min.js ../../build/node_modules/react/umd/react.development.js ../../build/node_modules/react-dom/umd/react-dom.development.js ../../build/node_modules/react/umd/react.production.min.js ../../build/node_modules/react-dom/umd/react-dom.production.min.js ../../build/node_modules/react-dom/umd/react-dom-server.browser.development.js ../../build/node_modules/react-dom/umd/react-dom-server.browser.production.min.js ../../build/node_modules/react-dom/umd/react-dom-test-utils.development.js ../../build/node_modules/react-dom/umd/react-dom-test-utils.production.min.js public/",
     "build": "react-scripts build && cp build/index.html build/200.html",
     "test": "react-scripts test --env=jsdom",
     "eject": "react-scripts eject"

fixtures/dom/public/act-dom.html

@@ -7,7 +7,11 @@
   this page tests whether act runs properly in a browser.
   <br/>
   your console should say "5"
+  <script src='scheduler-unstable_mock.development.js'></script>
   <script src='react.development.js'></script>
+  <script type="text/javascript">    
+    window.React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.Scheduler = window.SchedulerMock
+  </script>
   <script src='react-dom.development.js'></script>
   <script src='react-dom-test-utils.development.js'></script>
   <script>

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

@@ -0,0 +1,28 @@
+/**
+ * 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.
+ *
+ * @emails react-core
+ */
+
+let ReactFeatureFlags;
+let act;
+describe('mocked scheduler', () => {
+  beforeEach(() => {
+    jest.resetModules();
+    ReactFeatureFlags = require('shared/ReactFeatureFlags');
+    ReactFeatureFlags.warnAboutMissingMockScheduler = true;
+    jest.unmock('scheduler');
+    act = require('react-dom/test-utils').act;
+  });
+  it("should warn when the scheduler isn't mocked", () => {
+    expect(() => act(() => {})).toWarnDev(
+      [
+        'Starting from React v17, the "scheduler" module will need to be mocked',
+      ],
+      {withoutStack: true},
+    );
+  });
+});