Add test case for flattened children lists

facebook · May 30, 2024 · 49267d4 · 49267d4
1 parent 6b46ad9
commit 49267d4
Showing 1 changed file with 20 additions and 0 deletions.
diff --git a/packages/react/src/__tests__/ReactChildren-test.js b/packages/react/src/__tests__/ReactChildren-test.js
@@ -868,6 +868,26 @@ describe('ReactChildren', () => {
     ]);
   });
 
+  it('should warn for flattened children lists', async () => {
+    function ComponentRenderingFlattenedChildren({children}) {
+      return <div>{React.Children.toArray(children)}</div>;
+    }
+
+    const container = document.createElement('div');
+    const root = ReactDOMClient.createRoot(container);
+    await expect(async () => {
+      await act(() => {
+        root.render(
+          <ComponentRenderingFlattenedChildren>
+            {[<div />]}
+          </ComponentRenderingFlattenedChildren>,
+        );
+      });
+    }).toErrorDev([
+      'Warning: Each child in a list should have a unique "key" prop.',
+    ]);
+  });
+
   it('does not warn for flattened positional children', async () => {
     function ComponentRenderingFlattenedChildren({children}) {
       return <div>{React.Children.toArray(children)}</div>;