diff --git a/packages/react-dom/src/__tests__/ReactDOMServerSuspense-test.internal.js b/packages/react-dom/src/__tests__/ReactDOMServerSuspense-test.internal.js
index 535de142b36e2..78672c05f61c2 100644
--- a/packages/react-dom/src/__tests__/ReactDOMServerSuspense-test.internal.js
+++ b/packages/react-dom/src/__tests__/ReactDOMServerSuspense-test.internal.js
@@ -161,7 +161,7 @@ describe('ReactDOMServerSuspense', () => {
     expect(divB.tagName).toBe('DIV');
     expect(divB.textContent).toBe('B');
 
-    act(() => {
+    await act(async () => {
       ReactDOMClient.hydrateRoot(parent, example);
     });
 
diff --git a/packages/react-dom/src/__tests__/ReactDOMSuspensePlaceholder-test.js b/packages/react-dom/src/__tests__/ReactDOMSuspensePlaceholder-test.js
index 3fc477416d8f4..129ae2746dc21 100644
--- a/packages/react-dom/src/__tests__/ReactDOMSuspensePlaceholder-test.js
+++ b/packages/react-dom/src/__tests__/ReactDOMSuspensePlaceholder-test.js
@@ -153,7 +153,7 @@ describe('ReactDOMSuspensePlaceholder', () => {
         );
       }
 
-      act(() => {
+      await act(async () => {
         ReactDOM.render(<App />, container);
       });
       expect(container.innerHTML).toEqual(
@@ -161,15 +161,7 @@ describe('ReactDOMSuspensePlaceholder', () => {
           '"display: none;"></span>Loading...',
       );
 
-      act(() => setIsVisible(true));
-      expect(container.innerHTML).toEqual(
-        '<span style="display: none;">Sibling</span><span style=' +
-          '"display: none;"></span>Loading...',
-      );
-
-      await advanceTimers(500);
-
-      Scheduler.unstable_flushAll();
+      await act(async () => setIsVisible(true));
 
       expect(container.innerHTML).toEqual(
         '<span style="display: inline;">Sibling</span><span style="">Async</span>',
diff --git a/packages/react-native-renderer/src/__tests__/ReactFabric-test.internal.js b/packages/react-native-renderer/src/__tests__/ReactFabric-test.internal.js
index 2e5d41afa0212..7b7731018eb83 100644
--- a/packages/react-native-renderer/src/__tests__/ReactFabric-test.internal.js
+++ b/packages/react-native-renderer/src/__tests__/ReactFabric-test.internal.js
@@ -44,13 +44,13 @@ describe('ReactFabric', () => {
     act = require('jest-react').act;
   });
 
-  it('should be able to create and render a native component', () => {
+  it('should be able to create and render a native component', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {foo: true},
       uiViewClassName: 'RCTView',
     }));
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<View foo="test" />, 1);
     });
     expect(nativeFabricUIManager.createNode).toBeCalled();
@@ -58,7 +58,7 @@ describe('ReactFabric', () => {
     expect(nativeFabricUIManager.completeRoot).toBeCalled();
   });
 
-  it('should be able to create and update a native component', () => {
+  it('should be able to create and update a native component', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {foo: true},
       uiViewClassName: 'RCTView',
@@ -68,13 +68,13 @@ describe('ReactFabric', () => {
 
     nativeFabricUIManager.createNode.mockReturnValue(firstNode);
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<View foo="foo" />, 11);
     });
 
     expect(nativeFabricUIManager.createNode).toHaveBeenCalledTimes(1);
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<View foo="bar" />, 11);
     });
 
@@ -92,13 +92,13 @@ describe('ReactFabric', () => {
     });
   });
 
-  it('should not call FabricUIManager.cloneNode after render for properties that have not changed', () => {
+  it('should not call FabricUIManager.cloneNode after render for properties that have not changed', async () => {
     const Text = createReactNativeComponentClass('RCTText', () => ({
       validAttributes: {foo: true},
       uiViewClassName: 'RCTText',
     }));
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<Text foo="a">1</Text>, 11);
     });
     expect(nativeFabricUIManager.cloneNode).not.toBeCalled();
@@ -109,7 +109,7 @@ describe('ReactFabric', () => {
     ).not.toBeCalled();
 
     // If no properties have changed, we shouldn't call cloneNode.
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<Text foo="a">1</Text>, 11);
     });
     expect(nativeFabricUIManager.cloneNode).not.toBeCalled();
@@ -120,7 +120,7 @@ describe('ReactFabric', () => {
     ).not.toBeCalled();
 
     // Only call cloneNode for the changed property (and not for text).
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<Text foo="b">1</Text>, 11);
     });
     expect(nativeFabricUIManager.cloneNode).not.toBeCalled();
@@ -133,7 +133,7 @@ describe('ReactFabric', () => {
     ).not.toBeCalled();
 
     // Only call cloneNode for the changed text (and no other properties).
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<Text foo="b">2</Text>, 11);
     });
     expect(nativeFabricUIManager.cloneNode).not.toBeCalled();
@@ -148,7 +148,7 @@ describe('ReactFabric', () => {
     ).not.toBeCalled();
 
     // Call cloneNode for both changed text and properties.
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<Text foo="c">3</Text>, 11);
     });
     expect(nativeFabricUIManager.cloneNode).not.toBeCalled();
@@ -163,13 +163,13 @@ describe('ReactFabric', () => {
     ).toHaveBeenCalledTimes(1);
   });
 
-  it('should only pass props diffs to FabricUIManager.cloneNode', () => {
+  it('should only pass props diffs to FabricUIManager.cloneNode', async () => {
     const Text = createReactNativeComponentClass('RCTText', () => ({
       validAttributes: {foo: true, bar: true},
       uiViewClassName: 'RCTText',
     }));
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <Text foo="a" bar="a">
           1
@@ -184,7 +184,7 @@ describe('ReactFabric', () => {
       nativeFabricUIManager.cloneNodeWithNewChildrenAndProps,
     ).not.toBeCalled();
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <Text foo="a" bar="b">
           1
@@ -201,7 +201,7 @@ describe('ReactFabric', () => {
       nativeFabricUIManager.__dumpHierarchyForJestTestsOnly(),
     ).toMatchSnapshot();
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <Text foo="b" bar="b">
           2
@@ -219,7 +219,7 @@ describe('ReactFabric', () => {
     ).toMatchSnapshot();
   });
 
-  it('should call dispatchCommand for native refs', () => {
+  it('should call dispatchCommand for native refs', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {foo: true},
       uiViewClassName: 'RCTView',
@@ -228,7 +228,7 @@ describe('ReactFabric', () => {
     nativeFabricUIManager.dispatchCommand.mockClear();
 
     let viewRef;
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <View
           ref={ref => {
@@ -249,7 +249,7 @@ describe('ReactFabric', () => {
     );
   });
 
-  it('should warn and no-op if calling dispatchCommand on non native refs', () => {
+  it('should warn and no-op if calling dispatchCommand on non native refs', async () => {
     class BasicClass extends React.Component {
       render() {
         return <React.Fragment />;
@@ -259,7 +259,7 @@ describe('ReactFabric', () => {
     nativeFabricUIManager.dispatchCommand.mockReset();
 
     let viewRef;
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <BasicClass
           ref={ref => {
@@ -280,7 +280,7 @@ describe('ReactFabric', () => {
     expect(nativeFabricUIManager.dispatchCommand).not.toBeCalled();
   });
 
-  it('should call sendAccessibilityEvent for native refs', () => {
+  it('should call sendAccessibilityEvent for native refs', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {foo: true},
       uiViewClassName: 'RCTView',
@@ -289,7 +289,7 @@ describe('ReactFabric', () => {
     nativeFabricUIManager.sendAccessibilityEvent.mockClear();
 
     let viewRef;
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <View
           ref={ref => {
@@ -311,7 +311,7 @@ describe('ReactFabric', () => {
     );
   });
 
-  it('should warn and no-op if calling sendAccessibilityEvent on non native refs', () => {
+  it('should warn and no-op if calling sendAccessibilityEvent on non native refs', async () => {
     class BasicClass extends React.Component {
       render() {
         return <React.Fragment />;
@@ -321,7 +321,7 @@ describe('ReactFabric', () => {
     nativeFabricUIManager.sendAccessibilityEvent.mockReset();
 
     let viewRef;
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <BasicClass
           ref={ref => {
@@ -363,7 +363,7 @@ describe('ReactFabric', () => {
     expect(a).toBe(c);
   });
 
-  it('renders and reorders children', () => {
+  it('renders and reorders children', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {title: true},
       uiViewClassName: 'RCTView',
@@ -386,14 +386,14 @@ describe('ReactFabric', () => {
     const before = 'abcdefghijklmnopqrst';
     const after = 'mxhpgwfralkeoivcstzy';
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<Component chars={before} />, 11);
     });
     expect(
       nativeFabricUIManager.__dumpHierarchyForJestTestsOnly(),
     ).toMatchSnapshot();
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<Component chars={after} />, 11);
     });
     expect(
@@ -401,7 +401,7 @@ describe('ReactFabric', () => {
     ).toMatchSnapshot();
   });
 
-  it('recreates host parents even if only children changed', () => {
+  it('recreates host parents even if only children changed', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {title: true},
       uiViewClassName: 'RCTView',
@@ -428,7 +428,7 @@ describe('ReactFabric', () => {
 
     const ref = React.createRef();
     // Wrap in a host node.
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <View>
           <Component ref={ref} />
@@ -450,7 +450,7 @@ describe('ReactFabric', () => {
     ).toMatchSnapshot();
   });
 
-  it('calls setState with no arguments', () => {
+  it('calls setState with no arguments', async () => {
     let mockArgs;
     class Component extends React.Component {
       componentDidMount() {
@@ -461,13 +461,13 @@ describe('ReactFabric', () => {
       }
     }
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<Component />, 11);
     });
     expect(mockArgs.length).toEqual(0);
   });
 
-  it('should call complete after inserting children', () => {
+  it('should call complete after inserting children', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {foo: true},
       uiViewClassName: 'RCTView',
@@ -483,7 +483,7 @@ describe('ReactFabric', () => {
       );
     });
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <View foo="a">
           <View foo="b" />
@@ -494,7 +494,7 @@ describe('ReactFabric', () => {
     expect(snapshots).toMatchSnapshot();
   });
 
-  it('should not throw when <View> is used inside of a <Text> ancestor', () => {
+  it('should not throw when <View> is used inside of a <Text> ancestor', async () => {
     const Image = createReactNativeComponentClass('RCTImage', () => ({
       validAttributes: {},
       uiViewClassName: 'RCTImage',
@@ -508,7 +508,7 @@ describe('ReactFabric', () => {
       uiViewClassName: 'RCTView',
     }));
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <Text>
           <View />
@@ -517,7 +517,7 @@ describe('ReactFabric', () => {
       );
     });
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <Text>
           <Image />
@@ -527,7 +527,7 @@ describe('ReactFabric', () => {
     });
   });
 
-  it('should console error for text not inside of a <Text> ancestor', () => {
+  it('should console error for text not inside of a <Text> ancestor', async () => {
     const ScrollView = createReactNativeComponentClass('RCTScrollView', () => ({
       validAttributes: {},
       uiViewClassName: 'RCTScrollView',
@@ -541,14 +541,14 @@ describe('ReactFabric', () => {
       uiViewClassName: 'RCTView',
     }));
 
-    expect(() => {
-      act(() => {
+    await expect(async () => {
+      await act(async () => {
         ReactFabric.render(<View>this should warn</View>, 11);
       });
     }).toErrorDev(['Text strings must be rendered within a <Text> component.']);
 
-    expect(() => {
-      act(() => {
+    await expect(async () => {
+      await act(async () => {
         ReactFabric.render(
           <Text>
             <ScrollView>hi hello hi</ScrollView>
@@ -559,7 +559,7 @@ describe('ReactFabric', () => {
     }).toErrorDev(['Text strings must be rendered within a <Text> component.']);
   });
 
-  it('should not throw for text inside of an indirect <Text> ancestor', () => {
+  it('should not throw for text inside of an indirect <Text> ancestor', async () => {
     const Text = createReactNativeComponentClass('RCTText', () => ({
       validAttributes: {},
       uiViewClassName: 'RCTText',
@@ -567,7 +567,7 @@ describe('ReactFabric', () => {
 
     const Indirection = () => 'Hi';
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <Text>
           <Indirection />
@@ -577,7 +577,7 @@ describe('ReactFabric', () => {
     });
   });
 
-  it('dispatches events to the last committed props', () => {
+  it('dispatches events to the last committed props', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {},
       uiViewClassName: 'RCTView',
@@ -591,7 +591,7 @@ describe('ReactFabric', () => {
     const touchStart = jest.fn();
     const touchStart2 = jest.fn();
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<View onTouchStart={touchStart} />, 11);
     });
 
@@ -617,7 +617,7 @@ describe('ReactFabric', () => {
     expect(touchStart).toBeCalled();
     expect(touchStart2).not.toBeCalled();
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(<View onTouchStart={touchStart2} />, 11);
     });
 
@@ -631,7 +631,7 @@ describe('ReactFabric', () => {
   });
 
   describe('skipBubbling', () => {
-    it('should skip bubbling to ancestor if specified', () => {
+    it('should skip bubbling to ancestor if specified', async () => {
       const View = createReactNativeComponentClass('RCTView', () => ({
         validAttributes: {},
         uiViewClassName: 'RCTView',
@@ -665,7 +665,7 @@ describe('ReactFabric', () => {
 
       const event = {};
 
-      act(() => {
+      await act(async () => {
         ReactFabric.render(
           <View
             onSkippedBubblingEventCapture={ancestorCapture}
@@ -724,7 +724,7 @@ describe('ReactFabric', () => {
     });
   });
 
-  it('dispatches event with target as instance', () => {
+  it('dispatches event with target as instance', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {
         id: true,
@@ -752,7 +752,7 @@ describe('ReactFabric', () => {
     const ref1 = React.createRef();
     const ref2 = React.createRef();
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <View id="parent">
           <View
@@ -815,7 +815,7 @@ describe('ReactFabric', () => {
     expect.assertions(6);
   });
 
-  it('findHostInstance_DEPRECATED should warn if used to find a host component inside StrictMode', () => {
+  it('findHostInstance_DEPRECATED should warn if used to find a host component inside StrictMode', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {foo: true},
       uiViewClassName: 'RCTView',
@@ -834,7 +834,7 @@ describe('ReactFabric', () => {
       }
     }
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <ContainsStrictModeChild ref={n => (parent = n)} />,
         11,
@@ -856,7 +856,7 @@ describe('ReactFabric', () => {
     expect(match).toBe(child);
   });
 
-  it('findHostInstance_DEPRECATED should warn if passed a component that is inside StrictMode', () => {
+  it('findHostInstance_DEPRECATED should warn if passed a component that is inside StrictMode', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {foo: true},
       uiViewClassName: 'RCTView',
@@ -871,7 +871,7 @@ describe('ReactFabric', () => {
       }
     }
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <StrictMode>
           <IsInStrictMode ref={n => (parent = n)} />
@@ -895,7 +895,7 @@ describe('ReactFabric', () => {
     expect(match).toBe(child);
   });
 
-  it('findNodeHandle should warn if used to find a host component inside StrictMode', () => {
+  it('findNodeHandle should warn if used to find a host component inside StrictMode', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {foo: true},
       uiViewClassName: 'RCTView',
@@ -914,7 +914,7 @@ describe('ReactFabric', () => {
       }
     }
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <ContainsStrictModeChild ref={n => (parent = n)} />,
         11,
@@ -934,7 +934,7 @@ describe('ReactFabric', () => {
     expect(match).toBe(child._nativeTag);
   });
 
-  it('findNodeHandle should warn if passed a component that is inside StrictMode', () => {
+  it('findNodeHandle should warn if passed a component that is inside StrictMode', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {foo: true},
       uiViewClassName: 'RCTView',
@@ -949,7 +949,7 @@ describe('ReactFabric', () => {
       }
     }
 
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <StrictMode>
           <IsInStrictMode ref={n => (parent = n)} />
@@ -971,7 +971,7 @@ describe('ReactFabric', () => {
     expect(match).toBe(child._nativeTag);
   });
 
-  it('should no-op if calling sendAccessibilityEvent on unmounted refs', () => {
+  it('should no-op if calling sendAccessibilityEvent on unmounted refs', async () => {
     const View = createReactNativeComponentClass('RCTView', () => ({
       validAttributes: {foo: true},
       uiViewClassName: 'RCTView',
@@ -980,7 +980,7 @@ describe('ReactFabric', () => {
     nativeFabricUIManager.sendAccessibilityEvent.mockReset();
 
     let viewRef;
-    act(() => {
+    await act(async () => {
       ReactFabric.render(
         <View
           ref={ref => {
@@ -991,7 +991,7 @@ describe('ReactFabric', () => {
       );
     });
     const dangerouslyRetainedViewRef = viewRef;
-    act(() => {
+    await act(async () => {
       ReactFabric.stopSurface(11);
     });
 
diff --git a/packages/react-native-renderer/src/__tests__/ReactFabricHostComponent-test.internal.js b/packages/react-native-renderer/src/__tests__/ReactFabricHostComponent-test.internal.js
index cace77f902482..d816471b3e8a8 100644
--- a/packages/react-native-renderer/src/__tests__/ReactFabricHostComponent-test.internal.js
+++ b/packages/react-native-renderer/src/__tests__/ReactFabricHostComponent-test.internal.js
@@ -30,7 +30,7 @@ beforeEach(() => {
  * If the corresponding array of keys is null, the returned element at that
  * index will also be null.
  */
-function mockRenderKeys(keyLists) {
+async function mockRenderKeys(keyLists) {
   const ReactFabric = require('react-native-renderer/fabric');
   const createReactNativeComponentClass =
     require('react-native/Libraries/ReactPrivate/ReactNativePrivateInterface')
@@ -43,10 +43,12 @@ function mockRenderKeys(keyLists) {
     uiViewClassName: 'RCTMockView',
   }));
 
-  return keyLists.map(keyList => {
+  const result = [];
+  for (let i = 0; i < keyLists.length; i++) {
+    const keyList = keyLists[i];
     if (Array.isArray(keyList)) {
       const refs = keyList.map(key => undefined);
-      act(() => {
+      await act(async () => {
         ReactFabric.render(
           <MockView>
             {keyList.map((key, index) => (
@@ -62,27 +64,31 @@ function mockRenderKeys(keyLists) {
         );
       });
       // Clone `refs` to ignore future passes.
-      return [...refs];
+      result.push([...refs]);
+      continue;
     }
     if (keyList == null) {
-      act(() => {
+      await act(async () => {
         ReactFabric.stopSurface(mockContainerTag);
       });
-      return null;
+      result.push(null);
+      continue;
     }
     throw new TypeError(
       `Invalid 'keyLists' element of type ${typeof keyList}.`,
     );
-  });
+  }
+
+  return result;
 }
 
 describe('blur', () => {
-  test('blur() invokes TextInputState', () => {
+  test('blur() invokes TextInputState', async () => {
     const {
       TextInputState,
     } = require('react-native/Libraries/ReactPrivate/ReactNativePrivateInterface');
 
-    const [[fooRef]] = mockRenderKeys([['foo']]);
+    const [[fooRef]] = await mockRenderKeys([['foo']]);
 
     fooRef.blur();
 
@@ -91,12 +97,12 @@ describe('blur', () => {
 });
 
 describe('focus', () => {
-  test('focus() invokes TextInputState', () => {
+  test('focus() invokes TextInputState', async () => {
     const {
       TextInputState,
     } = require('react-native/Libraries/ReactPrivate/ReactNativePrivateInterface');
 
-    const [[fooRef]] = mockRenderKeys([['foo']]);
+    const [[fooRef]] = await mockRenderKeys([['foo']]);
 
     fooRef.focus();
 
@@ -105,8 +111,8 @@ describe('focus', () => {
 });
 
 describe('measure', () => {
-  test('component.measure(...) invokes callback', () => {
-    const [[fooRef]] = mockRenderKeys([['foo']]);
+  test('component.measure(...) invokes callback', async () => {
+    const [[fooRef]] = await mockRenderKeys([['foo']]);
 
     const callback = jest.fn();
     fooRef.measure(callback);
@@ -115,8 +121,8 @@ describe('measure', () => {
     expect(callback.mock.calls).toEqual([[10, 10, 100, 100, 0, 0]]);
   });
 
-  test('unmounted.measure(...) does nothing', () => {
-    const [[fooRef]] = mockRenderKeys([['foo'], null]);
+  test('unmounted.measure(...) does nothing', async () => {
+    const [[fooRef]] = await mockRenderKeys([['foo'], null]);
 
     const callback = jest.fn();
     fooRef.measure(callback);
@@ -127,8 +133,8 @@ describe('measure', () => {
 });
 
 describe('measureInWindow', () => {
-  test('component.measureInWindow(...) invokes callback', () => {
-    const [[fooRef]] = mockRenderKeys([['foo']]);
+  test('component.measureInWindow(...) invokes callback', async () => {
+    const [[fooRef]] = await mockRenderKeys([['foo']]);
 
     const callback = jest.fn();
     fooRef.measureInWindow(callback);
@@ -137,8 +143,8 @@ describe('measureInWindow', () => {
     expect(callback.mock.calls).toEqual([[10, 10, 100, 100]]);
   });
 
-  test('unmounted.measureInWindow(...) does nothing', () => {
-    const [[fooRef]] = mockRenderKeys([['foo'], null]);
+  test('unmounted.measureInWindow(...) does nothing', async () => {
+    const [[fooRef]] = await mockRenderKeys([['foo'], null]);
 
     const callback = jest.fn();
     fooRef.measureInWindow(callback);
@@ -149,8 +155,8 @@ describe('measureInWindow', () => {
 });
 
 describe('measureLayout', () => {
-  test('component.measureLayout(component, ...) invokes callback', () => {
-    const [[fooRef, barRef]] = mockRenderKeys([['foo', 'bar']]);
+  test('component.measureLayout(component, ...) invokes callback', async () => {
+    const [[fooRef, barRef]] = await mockRenderKeys([['foo', 'bar']]);
 
     const successCallback = jest.fn();
     const failureCallback = jest.fn();
@@ -160,8 +166,8 @@ describe('measureLayout', () => {
     expect(successCallback.mock.calls).toEqual([[1, 1, 100, 100]]);
   });
 
-  test('unmounted.measureLayout(component, ...) does nothing', () => {
-    const [[fooRef, barRef]] = mockRenderKeys([
+  test('unmounted.measureLayout(component, ...) does nothing', async () => {
+    const [[fooRef, barRef]] = await mockRenderKeys([
       ['foo', 'bar'],
       ['foo', null],
     ]);
@@ -174,8 +180,8 @@ describe('measureLayout', () => {
     expect(successCallback).not.toHaveBeenCalled();
   });
 
-  test('component.measureLayout(unmounted, ...) does nothing', () => {
-    const [[fooRef, barRef]] = mockRenderKeys([
+  test('component.measureLayout(unmounted, ...) does nothing', async () => {
+    const [[fooRef, barRef]] = await mockRenderKeys([
       ['foo', 'bar'],
       [null, 'bar'],
     ]);
@@ -188,8 +194,8 @@ describe('measureLayout', () => {
     expect(successCallback).not.toHaveBeenCalled();
   });
 
-  test('unmounted.measureLayout(unmounted, ...) does nothing', () => {
-    const [[fooRef, barRef]] = mockRenderKeys([['foo', 'bar'], null]);
+  test('unmounted.measureLayout(unmounted, ...) does nothing', async () => {
+    const [[fooRef, barRef]] = await mockRenderKeys([['foo', 'bar'], null]);
 
     const successCallback = jest.fn();
     const failureCallback = jest.fn();
@@ -201,8 +207,8 @@ describe('measureLayout', () => {
 });
 
 describe('unstable_getBoundingClientRect', () => {
-  test('component.unstable_getBoundingClientRect() returns DOMRect', () => {
-    const [[fooRef]] = mockRenderKeys([['foo']]);
+  test('component.unstable_getBoundingClientRect() returns DOMRect', async () => {
+    const [[fooRef]] = await mockRenderKeys([['foo']]);
 
     const rect = fooRef.unstable_getBoundingClientRect();
 
@@ -217,8 +223,8 @@ describe('unstable_getBoundingClientRect', () => {
     });
   });
 
-  test('unmounted.unstable_getBoundingClientRect() returns empty DOMRect', () => {
-    const [[fooRef]] = mockRenderKeys([['foo'], null]);
+  test('unmounted.unstable_getBoundingClientRect() returns empty DOMRect', async () => {
+    const [[fooRef]] = await mockRenderKeys([['foo'], null]);
 
     const rect = fooRef.unstable_getBoundingClientRect();
 
@@ -228,12 +234,12 @@ describe('unstable_getBoundingClientRect', () => {
 });
 
 describe('setNativeProps', () => {
-  test('setNativeProps(...) invokes setNativeProps on Fabric UIManager', () => {
+  test('setNativeProps(...) invokes setNativeProps on Fabric UIManager', async () => {
     const {
       UIManager,
     } = require('react-native/Libraries/ReactPrivate/ReactNativePrivateInterface');
 
-    const [[fooRef]] = mockRenderKeys([['foo']]);
+    const [[fooRef]] = await mockRenderKeys([['foo']]);
     fooRef.setNativeProps({foo: 'baz'});
 
     expect(UIManager.updateView).not.toBeCalled();
diff --git a/packages/react-reconciler/src/__tests__/ReactIncrementalScheduling-test.js b/packages/react-reconciler/src/__tests__/ReactIncrementalScheduling-test.js
index eb0044b30182e..1a76bacaa3b1e 100644
--- a/packages/react-reconciler/src/__tests__/ReactIncrementalScheduling-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactIncrementalScheduling-test.js
@@ -102,7 +102,7 @@ describe('ReactIncrementalScheduling', () => {
       return text;
     }
 
-    act(() => {
+    await act(async () => {
       ReactNoop.renderToRootWithID(<Text text="a:1" />, 'a');
       ReactNoop.renderToRootWithID(<Text text="b:1" />, 'b');
       ReactNoop.renderToRootWithID(<Text text="c:1" />, 'c');
diff --git a/packages/react-reconciler/src/__tests__/ReactNoopRendererAct-test.js b/packages/react-reconciler/src/__tests__/ReactNoopRendererAct-test.js
index 7be058b261e5f..8de0496bad9ed 100644
--- a/packages/react-reconciler/src/__tests__/ReactNoopRendererAct-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactNoopRendererAct-test.js
@@ -26,7 +26,7 @@ describe('internal act()', () => {
     }
 
     const calledLog = [];
-    act(() => {
+    await act(async () => {
       ReactNoop.render(
         <App
           callback={() => {
diff --git a/packages/react-reconciler/src/__tests__/ReactOffscreen-test.js b/packages/react-reconciler/src/__tests__/ReactOffscreen-test.js
index d35cacff3473c..937df702f1a84 100644
--- a/packages/react-reconciler/src/__tests__/ReactOffscreen-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactOffscreen-test.js
@@ -1992,7 +1992,7 @@ describe('ReactOffscreen', () => {
     }
 
     const root = ReactNoop.createRoot();
-    await act(() => {
+    await act(async () => {
       root.render(<App />);
     });
 
@@ -2052,7 +2052,7 @@ describe('ReactOffscreen', () => {
     }
 
     const root = ReactNoop.createRoot();
-    await act(() => {
+    await act(async () => {
       root.render(<App />);
     });
     assertLog(['attach child']);
diff --git a/packages/react-reconciler/src/__tests__/ReactThenable-test.js b/packages/react-reconciler/src/__tests__/ReactThenable-test.js
index ce5435d7fad06..fce0c0b173602 100644
--- a/packages/react-reconciler/src/__tests__/ReactThenable-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactThenable-test.js
@@ -782,7 +782,7 @@ describe('ReactThenable', () => {
     }
 
     const root = ReactNoop.createRoot();
-    await act(() => {
+    await act(async () => {
       root.render(<Parent />);
     });
     assertLog(['childShouldSuspend: false, showChild: true', 'Child']);
diff --git a/packages/react-reconciler/src/__tests__/ReactTransitionTracing-test.js b/packages/react-reconciler/src/__tests__/ReactTransitionTracing-test.js
index 08c331aefb84b..1d240498acf94 100644
--- a/packages/react-reconciler/src/__tests__/ReactTransitionTracing-test.js
+++ b/packages/react-reconciler/src/__tests__/ReactTransitionTracing-test.js
@@ -2208,7 +2208,7 @@ describe('ReactInteractionTracing', () => {
     const root = ReactNoop.createRoot({
       unstable_transitionCallbacks: transitionCallbacks,
     });
-    await act(() => {
+    await act(async () => {
       startTransition(() => root.render(<App />), {name: 'transition'});
       ReactNoop.expire(1000);
       advanceTimers(1000);
@@ -2221,7 +2221,7 @@ describe('ReactInteractionTracing', () => {
       'onTransitionStart(transition, 0)',
     ]);
 
-    await act(() => {
+    await act(async () => {
       resolveText('Text');
       ReactNoop.expire(1000);
       advanceTimers(1000);
@@ -2232,7 +2232,7 @@ describe('ReactInteractionTracing', () => {
       'onTransitionComplete(transition, 0, 2000)',
     ]);
 
-    await act(() => {
+    await act(async () => {
       resolveText('Hidden Text');
       ReactNoop.expire(1000);
       advanceTimers(1000);
@@ -2343,7 +2343,7 @@ describe('ReactInteractionTracing', () => {
       unstable_transitionCallbacks: transitionCallbacks,
     });
 
-    await act(() => {
+    await act(async () => {
       startTransition(() => root.render(<App />), {name: 'transition'});
       ReactNoop.expire(1000);
       advanceTimers(1000);
@@ -2361,7 +2361,7 @@ describe('ReactInteractionTracing', () => {
       'onTransitionProgress(transition, 0, 1000, [two])',
     ]);
 
-    await act(() => {
+    await act(async () => {
       resolveText('Text Two');
       ReactNoop.expire(1000);
       advanceTimers(1000);
@@ -2416,7 +2416,7 @@ describe('ReactInteractionTracing', () => {
       unstable_transitionCallbacks: getTransitionCallbacks('root two'),
     });
 
-    await act(() => {
+    await act(async () => {
       startTransition(() => rootOne.render(<App name="one" />), {
         name: 'transition one',
       });
@@ -2438,7 +2438,7 @@ describe('ReactInteractionTracing', () => {
       'onTransitionProgress(transition two, 0, 1000, [two]) /root two/',
     ]);
 
-    await act(() => {
+    await act(async () => {
       caches[0].resolve('Text one');
       ReactNoop.expire(1000);
       advanceTimers(1000);
@@ -2450,7 +2450,7 @@ describe('ReactInteractionTracing', () => {
       'onTransitionComplete(transition one, 0, 2000) /root one/',
     ]);
 
-    await act(() => {
+    await act(async () => {
       resolveText('Text two');
       ReactNoop.expire(1000);
       advanceTimers(1000);
diff --git a/packages/use-sync-external-store/src/__tests__/useSyncExternalStoreNative-test.js b/packages/use-sync-external-store/src/__tests__/useSyncExternalStoreNative-test.js
index ac4c0b8f4bb08..10e62b19a52c4 100644
--- a/packages/use-sync-external-store/src/__tests__/useSyncExternalStoreNative-test.js
+++ b/packages/use-sync-external-store/src/__tests__/useSyncExternalStoreNative-test.js
@@ -117,7 +117,7 @@ describe('useSyncExternalStore (userspace shim, server rendering)', () => {
     }
 
     const root = ReactNoop.createRoot();
-    await act(() => {
+    await act(async () => {
       root.render(<App />);
     });
     assertLog(['client']);
@@ -161,13 +161,13 @@ describe('useSyncExternalStore (userspace shim, server rendering)', () => {
     }
 
     const root = ReactNoop.createRoot();
-    act(() => root.render(<App />));
+    await act(async () => root.render(<App />));
 
     assertLog(['A0', 'B0']);
     expect(root).toMatchRenderedOutput('A0B0');
 
     // Update b but not a
-    await act(() => {
+    await act(async () => {
       store.set({a: 0, b: 1});
     });
     // Only b re-renders
@@ -175,7 +175,7 @@ describe('useSyncExternalStore (userspace shim, server rendering)', () => {
     expect(root).toMatchRenderedOutput('A0B1');
 
     // Update a but not b
-    await act(() => {
+    await act(async () => {
       store.set({a: 1, b: 1});
     });
     // Only a re-renders
diff --git a/packages/use-sync-external-store/src/__tests__/useSyncExternalStoreShared-test.js b/packages/use-sync-external-store/src/__tests__/useSyncExternalStoreShared-test.js
index 4c4bee7c05d45..f86557793e878 100644
--- a/packages/use-sync-external-store/src/__tests__/useSyncExternalStoreShared-test.js
+++ b/packages/use-sync-external-store/src/__tests__/useSyncExternalStoreShared-test.js
@@ -64,7 +64,8 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
     // The internal act implementation doesn't batch updates by default, since
     // it's mostly used to test concurrent mode. But since these tests run
     // in both concurrent and legacy mode, I'm adding batching here.
-    act = cb => internalAct(() => ReactDOM.unstable_batchedUpdates(cb));
+    act = async cb =>
+      await internalAct(async () => ReactDOM.unstable_batchedUpdates(cb));
 
     if (gate(flags => flags.source)) {
       // The `shim/with-selector` module composes the main
@@ -142,19 +143,19 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
     const container = document.createElement('div');
     const root = createRoot(container);
-    await act(() => root.render(<App />));
+    await act(async () => root.render(<App />));
 
     assertLog(['Initial']);
     expect(container.textContent).toEqual('Initial');
 
-    await act(() => {
+    await act(async () => {
       store.set('Updated');
     });
     assertLog(['Updated']);
     expect(container.textContent).toEqual('Updated');
   });
 
-  test('skips re-rendering if nothing changes', () => {
+  test('skips re-rendering if nothing changes', async () => {
     const store = createExternalStore('Initial');
 
     function App() {
@@ -164,13 +165,13 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
     const container = document.createElement('div');
     const root = createRoot(container);
-    act(() => root.render(<App />));
+    await act(async () => root.render(<App />));
 
     assertLog(['Initial']);
     expect(container.textContent).toEqual('Initial');
 
     // Update to the same value
-    act(() => {
+    await act(async () => {
       store.set('Initial');
     });
     // Should not re-render
@@ -192,19 +193,19 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
     const container = document.createElement('div');
     const root = createRoot(container);
-    await act(() => root.render(<App />));
+    await act(async () => root.render(<App />));
 
     assertLog([0]);
     expect(container.textContent).toEqual('0');
 
-    await act(() => {
+    await act(async () => {
       storeA.set(1);
     });
     assertLog([1]);
     expect(container.textContent).toEqual('1');
 
     // Switch stores and update in the same batch
-    act(() => {
+    await act(async () => {
       ReactDOM.flushSync(() => {
         // This update will be disregarded
         storeA.set(2);
@@ -216,7 +217,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
     expect(container.textContent).toEqual('0');
 
     // Update A
-    await act(() => {
+    await act(async () => {
       storeA.set(3);
     });
     // Nothing happened, because we're no longer subscribed to A
@@ -224,7 +225,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
     expect(container.textContent).toEqual('0');
 
     // Update B
-    await act(() => {
+    await act(async () => {
       storeB.set(1);
     });
     assertLog([1]);
@@ -254,13 +255,13 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
     const container = document.createElement('div');
     const root = createRoot(container);
-    act(() => root.render(<App />));
+    await act(async () => root.render(<App />));
 
     assertLog(['A0', 'B0']);
     expect(container.textContent).toEqual('A0B0');
 
     // Update b but not a
-    await act(() => {
+    await act(async () => {
       store.set({a: 0, b: 1});
     });
     // Only b re-renders
@@ -268,7 +269,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
     expect(container.textContent).toEqual('A0B1');
 
     // Update a but not b
-    await act(() => {
+    await act(async () => {
       store.set({a: 1, b: 1});
     });
     // Only a re-renders
@@ -295,7 +296,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
       const container = document.createElement('div');
       const root = createRoot(container);
-      act(() => root.render(<App />));
+      await act(async () => root.render(<App />));
       assertLog([0, 'Passive effect: 0']);
 
       // Schedule an update. We'll intentionally not use `act` so that we can
@@ -323,7 +324,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
     },
   );
 
-  test('mutating the store in between render and commit when getSnapshot has changed', () => {
+  test('mutating the store in between render and commit when getSnapshot has changed', async () => {
     const store = createExternalStore({a: 1, b: 1});
 
     const getSnapshotA = () => store.getState().a;
@@ -365,11 +366,11 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
     const container = document.createElement('div');
     const root = createRoot(container);
-    act(() => root.render(<App />));
+    await act(async () => root.render(<App />));
     assertLog(['A1']);
     expect(container.textContent).toEqual('A1');
 
-    act(() => {
+    await act(async () => {
       // Change getSnapshot and update the store in the same batch
       setStep(1);
     });
@@ -383,7 +384,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
     expect(container.textContent).toEqual('B2');
   });
 
-  test('mutating the store in between render and commit when getSnapshot has _not_ changed', () => {
+  test('mutating the store in between render and commit when getSnapshot has _not_ changed', async () => {
     // Same as previous test, but `getSnapshot` does not change
     const store = createExternalStore({a: 1, b: 1});
 
@@ -423,13 +424,13 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
     const container = document.createElement('div');
     const root = createRoot(container);
-    act(() => root.render(<App />));
+    await act(async () => root.render(<App />));
     assertLog(['A1']);
     expect(container.textContent).toEqual('A1');
 
     // This will cause a layout effect, and in the layout effect we'll update
     // the store
-    act(() => {
+    await act(async () => {
       setStep(1);
     });
     assertLog([
@@ -463,7 +464,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
     const container = document.createElement('div');
     const root = createRoot(container);
-    act(() =>
+    await act(async () =>
       root.render(
         <>
           <Child1 />
@@ -474,14 +475,14 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
     assertLog([0, 0]);
     expect(container.textContent).toEqual('00');
 
-    await act(() => {
+    await act(async () => {
       store.set(1);
     });
     assertLog([1, 1, 'Reset back to 0', 0, 0]);
     expect(container.textContent).toEqual('00');
   });
 
-  test('uses the latest getSnapshot, even if it changed in the same batch as a store update', () => {
+  test('uses the latest getSnapshot, even if it changed in the same batch as a store update', async () => {
     const store = createExternalStore({a: 0, b: 0});
 
     const getSnapshotA = () => store.getState().a;
@@ -497,11 +498,11 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
     const container = document.createElement('div');
     const root = createRoot(container);
-    act(() => root.render(<App />));
+    await act(async () => root.render(<App />));
     assertLog([0]);
 
     // Update the store and getSnapshot at the same time
-    act(() => {
+    await act(async () => {
       ReactDOM.flushSync(() => {
         setGetSnapshot(() => getSnapshotB);
         store.set({a: 1, b: 2});
@@ -546,7 +547,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
     const errorBoundary = React.createRef(null);
     const container = document.createElement('div');
     const root = createRoot(container);
-    act(() =>
+    await act(async () =>
       root.render(
         <ErrorBoundary ref={errorBoundary}>
           <App />
@@ -557,7 +558,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
     expect(container.textContent).toEqual('0');
 
     // Update that throws in a getSnapshot. We can catch it with an error boundary.
-    await act(() => {
+    await act(async () => {
       store.set({value: 1, throwInGetSnapshot: true, throwInIsEqual: false});
     });
     if (gate(flags => !flags.enableUseSyncExternalStoreShim)) {
@@ -573,7 +574,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
     expect(container.textContent).toEqual('Error in getSnapshot');
   });
 
-  test('Infinite loop if getSnapshot keeps returning new reference', () => {
+  test('Infinite loop if getSnapshot keeps returning new reference', async () => {
     const store = createExternalStore({});
 
     function App() {
@@ -584,8 +585,10 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
     const container = document.createElement('div');
     const root = createRoot(container);
 
-    expect(() => {
-      expect(() => act(() => root.render(<App />))).toThrow(
+    await expect(async () => {
+      expect(() =>
+        ReactDOM.flushSync(async () => root.render(<App />)),
+      ).toThrow(
         'Maximum update depth exceeded. This can happen when a component repeatedly ' +
           'calls setState inside componentWillUpdate or componentDidUpdate. React limits ' +
           'the number of nested updates to prevent infinite loops.',
@@ -610,15 +613,15 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
     // Initial render that reads a snapshot of NaN. This is OK because we use
     // Object.is algorithm to compare values.
-    await act(() => root.render(<App />));
+    await act(async () => root.render(<App />));
     expect(container.textContent).toEqual('NaN');
 
     // Update to real number
-    await act(() => store.set(123));
+    await act(async () => store.set(123));
     expect(container.textContent).toEqual('123');
 
     // Update back to NaN
-    await act(() => store.set('not a number'));
+    await act(async () => store.set('not a number'));
     expect(container.textContent).toEqual('NaN');
   });
 
@@ -646,13 +649,13 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
       const container = document.createElement('div');
       const root = createRoot(container);
-      act(() => root.render(<App />));
+      await act(async () => root.render(<App />));
 
       assertLog(['App', 'Selector', 'A0']);
       expect(container.textContent).toEqual('A0');
 
       // Update the store
-      await act(() => {
+      await act(async () => {
         store.set({a: 1, b: 0});
       });
       assertLog([
@@ -705,13 +708,13 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
       const container = document.createElement('div');
       const root = createRoot(container);
-      act(() => root.render(<App />));
+      await act(async () => root.render(<App />));
 
       assertLog(['A0', 'B0']);
       expect(container.textContent).toEqual('A0B0');
 
       // Update b but not a
-      await act(() => {
+      await act(async () => {
         store.set({a: 0, b: 1});
       });
       // Only b re-renders
@@ -719,7 +722,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
       expect(container.textContent).toEqual('A0B1');
 
       // Update a but not b
-      await act(() => {
+      await act(async () => {
         store.set({a: 1, b: 1});
       });
       // Only a re-renders
@@ -752,7 +755,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
       const serverRenderedDiv = container.getElementsByTagName('div')[0];
 
       if (gate(flags => !flags.enableUseSyncExternalStoreShim)) {
-        act(() => {
+        await act(async () => {
           ReactDOMClient.hydrateRoot(container, <App />);
         });
         assertLog([
@@ -768,7 +771,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
         // currently hydrating, so `getServerSnapshot` is not called on the
         // client. To avoid this server mismatch warning, user must account for
         // this themselves and return the correct value inside `getSnapshot`.
-        act(() => {
+        await act(async () => {
           expect(() => ReactDOM.hydrate(<App />, container)).toErrorDev(
             'Text content did not match',
           );
@@ -795,12 +798,12 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
     const container = document.createElement('div');
     const root = createRoot(container);
-    await act(() => root.render(<App />));
+    await act(async () => root.render(<App />));
 
     assertLog(['INITIAL']);
     expect(container.textContent).toEqual('INITIAL');
 
-    await act(() => {
+    await act(async () => {
       store.set('Updated');
     });
     assertLog(['UPDATED']);
@@ -858,12 +861,12 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
     const container = document.createElement('div');
     const root = createRoot(container);
-    await act(() => {
+    await act(async () => {
       root.render(<App step={0} />);
     });
     assertLog(['Inline selector', 'A', 'B', 'C', 'Sibling: 0']);
 
-    await act(() => {
+    await act(async () => {
       root.render(<App step={1} />);
     });
     assertLog([
@@ -918,7 +921,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
       const container = document.createElement('div');
       const root = createRoot(container);
-      await act(() =>
+      await act(async () =>
         root.render(
           <ErrorBoundary>
             <App />
@@ -963,7 +966,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
 
       const container = document.createElement('div');
       const root = createRoot(container);
-      await act(() =>
+      await act(async () =>
         root.render(
           <ErrorBoundary>
             <App />
@@ -974,7 +977,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
       expect(container.textContent).toEqual('A');
 
       await expect(async () => {
-        await act(() => {
+        await act(async () => {
           store.set({});
         });
       }).toWarnDev(