Add regression test for stuck pending state

Introduces a regression test for a bug where the pending state of a
useTransition hook is not set back to `false` if it comes after a
`use` that suspended.

Co-authored-by: Andrew Clark <git@andrewclark.io>

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

@@ -16,8 +16,10 @@ let act;
 let use;
 let useDebugValue;
 let useState;
+let useTransition;
 let useMemo;
 let useEffect;
+let useOptimistic;
 let Suspense;
 let startTransition;
 let pendingTextRequests;
@@ -38,8 +40,10 @@ describe('ReactUse', () => {
     use = React.use;
     useDebugValue = React.useDebugValue;
     useState = React.useState;
+    useTransition = React.useTransition;
     useMemo = React.useMemo;
     useEffect = React.useEffect;
+    useOptimistic = React.useOptimistic;
     Suspense = React.Suspense;
     startTransition = React.startTransition;
 
@@ -1915,4 +1919,39 @@ describe('ReactUse', () => {
     assertLog(['Hi', 'World']);
     expect(root).toMatchRenderedOutput(<div>Hi World</div>);
   });
+
+  it('regression: does not get stuck in pending state after `use` suspends', async () => {
+    // This is a regression test. The root cause was an issue where we failed to
+    // switch from the "re-render" dispatcher back to the "update" dispatcher
+    // after a `use` suspends and triggers a replay.
+    let update;
+    function App({promise}) {
+      useState(false);
+
+      const value = use(promise);
+
+      const [isPending, startLocalTransition] = useTransition();
+      update = () => {
+        startLocalTransition(() => {
+          root.render(<App promise={getAsyncText('Updated')} />);
+        });
+      };
+
+      return <Text text={value + (isPending ? ' (pending...)' : '')} />;
+    }
+
+    const root = ReactNoop.createRoot();
+    await act(() => {
+      root.render(<App promise={Promise.resolve('Initial')} />);
+    });
+    assertLog(['Initial']);
+    expect(root).toMatchRenderedOutput('Initial');
+
+    await act(() => update());
+    assertLog(['Async text requested [Updated]', 'Initial (pending...)']);
+
+    await act(() => resolveTextRequests('Updated'));
+    assertLog(['Updated']);
+    expect(root).toMatchRenderedOutput('Updated');
+  });
 });