Further improve the tests

Author: djhi

packages/ra-core/src/controller/list/ListBase.spec.tsx

@@ -175,6 +175,7 @@ describe('ListBase', () => {
     });
     it('should render nothing while loading if emptyWhileLoading is set to true and using the render prop', async () => {
         render(<EmptyWhileLoadingRender />);
+        expect(screen.queryByText('Loading...')).toBeNull();
         expect(screen.queryByText('War and Peace')).toBeNull();
         fireEvent.click(screen.getByText('Resolve books loading'));
         await screen.findByText('War and Peace');

packages/ra-core/src/controller/list/ListBase.stories.tsx

@@ -493,13 +493,17 @@ export const EmptyWhileLoadingRender = () => {
                 resource="books"
                 perPage={5}
                 emptyWhileLoading
-                render={({ data }) => (
-                    <ul>
-                        {data.map((record: any) => (
-                            <li key={record.id}>{record.title}</li>
-                        ))}
-                    </ul>
-                )}
+                render={({ isPending, data }) =>
+                    isPending ? (
+                        <p>Loading...</p>
+                    ) : (
+                        <ul>
+                            {data.map((record: any) => (
+                                <li key={record.id}>{record.title}</li>
+                            ))}
+                        </ul>
+                    )
+                }
             />
         </CoreAdminContext>
     );