[TreeView] Set focus on the focused Tree Item instead of the Tree View

docs/data/migration/migration-tree-view-v6/migration-tree-view-v6.md

@@ -329,6 +329,34 @@ you can use the new `onNodeSelectionToggle` prop which is called whenever a node
 
 :::
 
+### Focus the Tree Item instead of the Tree View
+
+The focus is now applied to the Tree Item root element instead of the Tree View root element.
+This will mostly impact how you write tests to interact with the Tree View:
+
+For example, if you were writing a test with `react-testing-library`, here is what the changes could look like:
+
+```diff
+ it('test example on first item', () => {
+-  const { getByRole } = render(
++  const { getAllByRole } = render(
+     <SimpleTreeView>
+       <TreeItem nodeId="one" />
+       <TreeItem nodeId="two" />
+    </SimpleTreeView>
+   );
+
+-  const tree = getByRole('tree');
++  const firstTreeItem = getAllByRole('treeitem')[0];
+   act(() => {
+-    tree.focus();
++    firstTreeItem.focus();
+   });
+-  fireEvent.keyDown(tree, { key: 'ArrowDown' });
++  fireEvent.keyDown(firstTreeItem, { key: 'ArrowDown' });
+ })
+```
+
 ### ✅ Use `useTreeItemState` instead of `useTreeItem`
 
 The `useTreeItem` hook has been renamed `useTreeItemState`.