Internal act: Flush timers at end of scope

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

@@ -126,8 +126,9 @@ export function unstable_concurrentAct(scope: () => Thenable<mixed> | void) {
 }
 
 function flushActWork(resolve, reject) {
-  // TODO: Run timers to flush suspended fallbacks
-  // jest.runOnlyPendingTimers();
+  // Flush suspended fallbacks
+  // $FlowFixMe: Flow doesn't know about global Jest object
+  jest.runOnlyPendingTimers();
   enqueueTask(() => {
     try {
       const didFlushWork = Scheduler.unstable_flushAllWithoutAsserting();

packages/react-noop-renderer/src/createReactNoop.js

@@ -1175,8 +1175,9 @@ function createReactNoop(reconciler: Function, useMutation: boolean) {
   }
 
   function flushActWork(resolve, reject) {
-    // TODO: Run timers to flush suspended fallbacks
-    // jest.runOnlyPendingTimers();
+    // Flush suspended fallbacks
+    // $FlowFixMe: Flow doesn't know about global Jest object
+    jest.runOnlyPendingTimers();
     enqueueTask(() => {
       try {
         const didFlushWork = Scheduler.unstable_flushAllWithoutAsserting();

packages/react-reconciler/src/__tests__/ReactBlocks-test.js

@@ -14,6 +14,7 @@ let useState;
 let Suspense;
 let block;
 let readString;
+let resolvePromises;
 let Scheduler;
 
 describe('ReactBlocks', () => {
@@ -28,15 +29,16 @@ describe('ReactBlocks', () => {
     useState = React.useState;
     Suspense = React.Suspense;
     const cache = new Map();
+    let unresolved = [];
     readString = function(text) {
       let entry = cache.get(text);
       if (!entry) {
         entry = {
           promise: new Promise(resolve => {
-            setTimeout(() => {
+            unresolved.push(() => {
               entry.resolved = true;
               resolve();
-            }, 100);
+            });
           }),
           resolved: false,
         };
@@ -47,6 +49,12 @@ describe('ReactBlocks', () => {
       }
       return text;
     };
+
+    resolvePromises = () => {
+      const res = unresolved;
+      unresolved = [];
+      res.forEach(r => r());
+    };
   });
 
   // @gate experimental
@@ -144,7 +152,7 @@ describe('ReactBlocks', () => {
     expect(ReactNoop).toMatchRenderedOutput('Loading...');
 
     await ReactNoop.act(async () => {
-      jest.advanceTimersByTime(1000);
+      resolvePromises();
     });
 
     expect(ReactNoop).toMatchRenderedOutput(<span>Name: Sebastian</span>);
@@ -291,7 +299,7 @@ describe('ReactBlocks', () => {
       ReactNoop.render(<App Page={loadParent('Sebastian')} />);
     });
     await ReactNoop.act(async () => {
-      jest.advanceTimersByTime(1000);
+      resolvePromises();
     });
     expect(ReactNoop).toMatchRenderedOutput(<span>Name: Sebastian</span>);
   });
@@ -336,7 +344,7 @@ describe('ReactBlocks', () => {
     });
     await ReactNoop.act(async () => {
       _setSuspend(false);
-      jest.advanceTimersByTime(1000);
+      resolvePromises();
     });
     expect(ReactNoop).toMatchRenderedOutput(<span>Sebastian</span>);
   });

packages/react-reconciler/src/__tests__/ReactSuspenseWithNoopRenderer-test.js

@@ -575,7 +575,7 @@ describe('ReactSuspenseWithNoopRenderer', () => {
         <Suspense fallback="Loading...">
           <Text text="Sibling" />
           {shouldSuspend ? (
-            <AsyncText ms={10000} text={'Step ' + step} />
+            <AsyncText text={'Step ' + step} />
           ) : (
             <Text text={'Step ' + step} />
           )}
@@ -2595,7 +2595,7 @@ describe('ReactSuspenseWithNoopRenderer', () => {
           }
           return (
             <Suspense fallback={<Text text="Loading..." />}>
-              <AsyncText text={page} ms={5000} />
+              <AsyncText text={page} />
             </Suspense>
           );
         }
@@ -2616,8 +2616,7 @@ describe('ReactSuspenseWithNoopRenderer', () => {
       });
 
       // Later we load the data.
-      Scheduler.unstable_advanceTime(5000);
-      await advanceTimers(5000);
+      await resolveText('A');
       expect(Scheduler).toHaveYielded(['Promise resolved [A]']);
       expect(Scheduler).toFlushAndYield(['A']);
       expect(ReactNoop.getChildren()).toEqual([span('A')]);
@@ -2635,8 +2634,7 @@ describe('ReactSuspenseWithNoopRenderer', () => {
       });
 
       // Later we load the data.
-      Scheduler.unstable_advanceTime(3000);
-      await advanceTimers(3000);
+      await resolveText('B');
       expect(Scheduler).toHaveYielded(['Promise resolved [B]']);
       expect(Scheduler).toFlushAndYield(['B']);
       expect(ReactNoop.getChildren()).toEqual([span('B')]);
@@ -2754,12 +2752,14 @@ describe('ReactSuspenseWithNoopRenderer', () => {
     );
   });
 
+  // TODO: This test is specifically about avoided commits that suspend for a
+  // JND. We may remove this behavior.
   it("suspended commit remains suspended even if there's another update at same expiration", async () => {
     // Regression test
     function App({text}) {
       return (
         <Suspense fallback="Loading...">
-          <AsyncText ms={2000} text={text} />
+          <AsyncText text={text} />
         </Suspense>
       );
     }
@@ -2768,34 +2768,28 @@ describe('ReactSuspenseWithNoopRenderer', () => {
     await ReactNoop.act(async () => {
       root.render(<App text="Initial" />);
     });
+    expect(Scheduler).toHaveYielded(['Suspend! [Initial]']);
 
     // Resolve initial render
     await ReactNoop.act(async () => {
-      Scheduler.unstable_advanceTime(2000);
-      await advanceTimers(2000);
+      await resolveText('Initial');
     });
-    expect(Scheduler).toHaveYielded([
-      'Suspend! [Initial]',
-      'Promise resolved [Initial]',
-      'Initial',
-    ]);
+    expect(Scheduler).toHaveYielded(['Promise resolved [Initial]', 'Initial']);
     expect(root).toMatchRenderedOutput(<span prop="Initial" />);
 
-    // Update. Since showing a fallback would hide content that's already
-    // visible, it should suspend for a bit without committing.
     await ReactNoop.act(async () => {
+      // Update. Since showing a fallback would hide content that's already
+      // visible, it should suspend for a JND without committing.
       root.render(<App text="First update" />);
-
       expect(Scheduler).toFlushAndYield(['Suspend! [First update]']);
+
       // Should not display a fallback
       expect(root).toMatchRenderedOutput(<span prop="Initial" />);
-    });
 
-    // Update again. This should also suspend for a bit.
-    await ReactNoop.act(async () => {
+      // Update again. This should also suspend for a JND.
       root.render(<App text="Second update" />);
-
       expect(Scheduler).toFlushAndYield(['Suspend! [Second update]']);
+
       // Should not display a fallback
       expect(root).toMatchRenderedOutput(<span prop="Initial" />);
     });
@@ -3989,9 +3983,6 @@ describe('ReactSuspenseWithNoopRenderer', () => {
     await ReactNoop.act(async () => {
       root.render(<App show={true} />);
     });
-    // TODO: `act` should have already flushed the placeholder, so this
-    // runAllTimers call should be unnecessary.
-    jest.runAllTimers();
     expect(Scheduler).toHaveYielded(['Suspend! [Async]', 'Loading...']);
     expect(root).toMatchRenderedOutput(
       <>

packages/react-test-renderer/src/ReactTestRenderer.js

@@ -684,8 +684,9 @@ function unstable_concurrentAct(scope: () => Thenable<mixed> | void) {
 }
 
 function flushActWork(resolve, reject) {
-  // TODO: Run timers to flush suspended fallbacks
-  // jest.runOnlyPendingTimers();
+  // Flush suspended fallbacks
+  // $FlowFixMe: Flow doesn't know about global Jest object
+  jest.runOnlyPendingTimers();
   enqueueTask(() => {
     try {
       const didFlushWork = Scheduler.unstable_flushAllWithoutAsserting();

scripts/rollup/validate/eslintrc.cjs.js

@@ -42,6 +42,7 @@ module.exports = {
 
     // jest
     expect: true,
+    jest: true,
   },
   parserOptions: {
     ecmaVersion: 5,

scripts/rollup/validate/eslintrc.cjs2015.js

@@ -42,6 +42,7 @@ module.exports = {
 
     // jest
     expect: true,
+    jest: true,
   },
   parserOptions: {
     ecmaVersion: 2015,

scripts/rollup/validate/eslintrc.fb.js

@@ -36,6 +36,9 @@ module.exports = {
     // Flight
     Uint8Array: true,
     Promise: true,
+
+    // jest
+    jest: true,
   },
   parserOptions: {
     ecmaVersion: 5,

scripts/rollup/validate/eslintrc.rn.js

@@ -31,6 +31,9 @@ module.exports = {
     ArrayBuffer: true,
 
     TaskController: true,
+
+    // jest
+    jest: true,
   },
   parserOptions: {
     ecmaVersion: 5,

scripts/rollup/validate/eslintrc.umd.js

@@ -43,6 +43,9 @@ module.exports = {
     // Flight Webpack
     __webpack_chunk_load__: true,
     __webpack_require__: true,
+
+    // jest
+    jest: true,
   },
   parserOptions: {
     ecmaVersion: 5,