test(app-shell): wait for the counted backfill checkbox in the unchecked publish case (objectui#13120)

.changeset/13120-backfill-checkbox-wait.md

@@ -0,0 +1,4 @@
+---
+---
+
+No package released: test only. Two `@object-ui/app-shell` backfill tests now wait for the backfill checkbox's counted name instead of reading it synchronously: the Studio publish-backfill test's unchecked case (as its other two cases already did), and the pending-changes sheet's "one choice" case. The drill-in reads the record count after the option renders, so a synchronous read raced that count on a slow runner (objectui#13120). No source, export, type or behaviour changes.

packages/app-shell/src/preview/__tests__/DraftChangesPanel.backfill-12929.test.tsx

@@ -114,7 +114,9 @@ describe('the backfill choice is offered only where the batch door would honour
     await settled();
     const options = await screen.findAllByTestId('draft-backfill-option');
     expect(options).toHaveLength(1);
-    const box = screen.getByRole('checkbox', { name: 'Backfill default (12 existing records)' });
+    // Waited for: the drill-in reads the count only after the option draws, so the
+    // name carries no number until that read lands.
+    const box = await screen.findByRole('checkbox', { name: 'Backfill default (12 existing records)' });
     expect(box).not.toBeChecked();
     // The literal the door would write is shown beside it.
     expect(options[0]).toHaveTextContent('= false');

packages/app-shell/src/views/studio-design/StudioDesignSurface.publishBackfill-12929.test.tsx

@@ -160,7 +160,14 @@ afterEach(() => {
   vi.unstubAllGlobals();
 });
 
-/** Open the sheet the way the author does: the header's Publish, which opens it to confirm. */
+/**
+ * Open the sheet the way the author does: the header's Publish, which opens it to confirm.
+ *
+ * Resolves once the backfill option is drawn, NOT once its count is: the drill-in
+ * asks the adapter for the record count only after the option renders, and names
+ * no number until that read lands. A read of the counted name (N) is therefore a
+ * waiting `findByRole`, never a synchronous `getByRole`, which races the count.
+ */
 async function openSheet(): Promise<HTMLElement> {
   render(
     <MemoryRouter initialEntries={[`/studio/${PACKAGE_ID}/interfaces`]}>
@@ -228,7 +235,8 @@ describe('Studio publish with the default backfill (objectui#12929)', () => {
 
   it('unchecked: the publish names no field, so nothing is written into existing rows', async () => {
     const sheet = await openSheet();
-    expect(within(sheet).getByRole('checkbox', { name: new RegExp(`\\b${N}\\b`) })).not.toBeChecked();
+    // Waited for, like the cases above: the count lands after the option draws.
+    expect(await within(sheet).findByRole('checkbox', { name: new RegExp(`\\b${N}\\b`) })).not.toBeChecked();
 
     fireEvent.click(within(sheet).getByTestId('draft-changes-publish'));