[tests] Fix assertions not flushed before act (#28745)

Fixes some easy cases blocking
#28737, I'll follow up with more
complex/interesting cases in other PRs.

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

@@ -913,15 +913,13 @@ describe('ReactCompositeComponent', () => {
     await act(() => {
       root.render(<Wrapper name="A" />);
     });
+
+    assertLog(['A componentWillMount', 'A render', 'A componentDidMount']);
     await act(() => {
       root.render(<Wrapper name="B" />);
     });
 
     assertLog([
-      'A componentWillMount',
-      'A render',
-      'A componentDidMount',
-
       'B componentWillMount',
       'B render',
       'A componentWillUnmount',

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

@@ -111,9 +111,11 @@ describe('ReactDOMFizzForm', () => {
       await readIntoContainer(stream);
       expect(container.textContent).toEqual('Loading...');
 
+      assertLog(['Loading...']);
       // After hydration, it's updated to the final value
       await act(() => ReactDOMClient.hydrateRoot(container, <App />));
       expect(container.textContent).toEqual('Final');
+      assertLog(['Loading...', 'Final']);
     },
   );
 

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

@@ -297,6 +297,7 @@ describe('ReactDOMNativeEventHeuristic-test', () => {
     });
     expect(container.textContent).toEqual('not hovered');
 
+    assertLog(['not hovered']);
     await act(async () => {
       // Note: React does not use native mouseenter/mouseleave events
       // but we should still correctly determine their priority.
@@ -308,7 +309,7 @@ describe('ReactDOMNativeEventHeuristic-test', () => {
       dispatchAndSetCurrentEvent(target.current, mouseEnterEvent);
 
       // Since mouse end is not discrete, should not have updated yet
-      assertLog(['not hovered']);
+      assertLog([]);
       expect(container.textContent).toEqual('not hovered');
 
       await waitFor(['hovered']);

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

@@ -342,12 +342,13 @@ describe('ReactDOMRoot', () => {
       root.render(<Foo value="a" />);
     });
 
+    assertLog(['a']);
     expect(container.textContent).toEqual('a');
 
     await act(async () => {
       root.render(<Foo value="b" />);
 
-      assertLog(['a']);
+      assertLog([]);
       expect(container.textContent).toEqual('a');
 
       await waitFor(['b']);

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

@@ -17,6 +17,7 @@ let Suspense;
 let Scheduler;
 let act;
 let textCache;
+let assertLog;
 
 describe('ReactDOMSuspensePlaceholder', () => {
   let container;
@@ -31,6 +32,7 @@ describe('ReactDOMSuspensePlaceholder', () => {
     ReactDOMClient = require('react-dom/client');
     Scheduler = require('scheduler');
     act = require('internal-test-utils').act;
+    assertLog = require('internal-test-utils').assertLog;
     Suspense = React.Suspense;
     container = document.createElement('div');
     document.body.appendChild(container);
@@ -157,11 +159,11 @@ describe('ReactDOMSuspensePlaceholder', () => {
     });
 
     expect(container.textContent).toEqual('Loading...');
-
+    assertLog(['A', 'Suspend! [B]', 'Loading...']);
     await act(() => {
       resolveText('B');
     });
-
+    assertLog(['A', 'B', 'C']);
     expect(container.textContent).toEqual('ABC');
   });
 

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

@@ -115,17 +115,14 @@ describe('ReactEmptyComponent', () => {
         root1.render(instance1);
       });
 
+      assertLog(['mount undefined', 'update DIV']);
+
       const root2 = ReactDOMClient.createRoot(container2);
       await act(() => {
         root2.render(instance2);
       });
 
-      assertLog([
-        'mount undefined',
-        'update DIV',
-        'mount DIV',
-        'update undefined',
-      ]);
+      assertLog(['mount DIV', 'update undefined']);
     });
 
     it('should be able to switch in a list of children', async () => {

packages/react-reconciler/src/__tests__/ReactUpdaters-test.internal.js

@@ -112,11 +112,13 @@ describe('updaters', () => {
       root.render(<Parent />);
     });
     expect(allSchedulerTags).toEqual([[HostRoot]]);
+    assertLog(['onCommitRoot']);
 
     await act(() => {
       root.render(<Parent />);
     });
     expect(allSchedulerTags).toEqual([[HostRoot], [HostRoot]]);
+    assertLog(['onCommitRoot']);
   });
 
   it('should report a function component as the scheduler for a hooks update', async () => {
@@ -148,12 +150,13 @@ describe('updaters', () => {
     expect(scheduleForA).not.toBeNull();
     expect(scheduleForB).not.toBeNull();
     expect(allSchedulerTypes).toEqual([[null]]);
+    assertLog(['onCommitRoot']);
 
     await act(() => {
       scheduleForA();
     });
     expect(allSchedulerTypes).toEqual([[null], [SchedulingComponentA]]);
-
+    assertLog(['onCommitRoot']);
     await act(() => {
       scheduleForB();
     });
@@ -162,6 +165,7 @@ describe('updaters', () => {
       [SchedulingComponentA],
       [SchedulingComponentB],
     ]);
+    assertLog(['onCommitRoot']);
   });
 
   it('should report a class component as the scheduler for a setState update', async () => {
@@ -180,7 +184,7 @@ describe('updaters', () => {
       root.render(<Parent />);
     });
     expect(allSchedulerTypes).toEqual([[null]]);
-
+    assertLog(['onCommitRoot']);
     expect(instance).not.toBeNull();
     await act(() => {
       instance.setState({});

packages/use-subscription/src/__tests__/useSubscription-test.js

@@ -338,20 +338,16 @@ describe('useSubscription', () => {
       observableB.next('b-3');
     });
 
+    assertLog(['Grandchild: b-0', 'Child: b-3', 'Grandchild: b-3']);
+
     // Update again
     await act(() => root.render(<Parent observed={observableA} />));
 
     // Flush everything and ensure that the correct subscribable is used
     // We expect the last emitted update to be rendered (because of the commit phase value check)
     // But the intermediate ones should be ignored,
     // And the final rendered output should be the higher-priority observable.
-    assertLog([
-      'Grandchild: b-0',
-      'Child: b-3',
-      'Grandchild: b-3',
-      'Child: a-0',
-      'Grandchild: a-0',
-    ]);
+    assertLog(['Child: a-0', 'Grandchild: a-0']);
     expect(log).toEqual([
       'Parent.componentDidMount',
       'Parent.componentDidUpdate',

packages/use-sync-external-store/src/__tests__/useSyncExternalStoreShared-test.js

@@ -660,14 +660,17 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
     // Object.is algorithm to compare values.
     await act(() => root.render(<App />));
     expect(container.textContent).toEqual('NaN');
+    assertLog([NaN]);
 
     // Update to real number
     await act(() => store.set(123));
     expect(container.textContent).toEqual('123');
+    assertLog([123]);
 
     // Update back to NaN
     await act(() => store.set('not a number'));
     expect(container.textContent).toEqual('NaN');
+    assertLog([NaN]);
   });
 
   describe('extra features implemented in user-space', () => {
@@ -968,6 +971,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
         ),
       );
 
+      assertLog(['A']);
       expect(container.textContent).toEqual('A');
 
       if (__DEV__ && gate(flags => flags.enableUseSyncExternalStoreShim)) {
@@ -1017,6 +1021,7 @@ describe('Shared useSyncExternalStore behavior (shim and built-in)', () => {
         ),
       );
 
+      assertLog(['A']);
       expect(container.textContent).toEqual('A');
 
       if (__DEV__ && gate(flags => flags.enableUseSyncExternalStoreShim)) {