[TreeView] Throw an error when two items have the same id

packages/x-tree-view/src/internals/plugins/useTreeViewJSXNodes/useTreeViewJSXNodes.tsx

@@ -17,7 +17,19 @@ export const useTreeViewJSXNodes: TreeViewPlugin<UseTreeViewJSXNodesSignature> =
   setState,
 }) => {
   const insertJSXNode = useEventCallback((node: TreeViewNode) => {
-    setState((prevState) => ({ ...prevState, nodeMap: { ...prevState.nodeMap, [node.id]: node } }));
+    setState((prevState) => {
+      if (prevState.nodeMap[node.id] != null) {
+        throw new Error(
+          [
+            'MUI X: The Tree View component requires all items to have a unique `id` property.',
+            'Alternatively, you can use the `getItemId` prop to specify a custom id for each item.',
+            `Tow items were provided with the same id in the \`items\` prop: "${node.id}"`,
+          ].join('\n'),
+        );
+      }
+
+      return { ...prevState, nodeMap: { ...prevState.nodeMap, [node.id]: node } };
+    });
   });
 
   const removeJSXNode = useEventCallback((nodeId: string) => {

packages/x-tree-view/src/internals/plugins/useTreeViewNodes/useTreeViewNodes.test.tsx

@@ -0,0 +1,60 @@
+import * as React from 'react';
+import { expect } from 'chai';
+import { createRenderer, ErrorBoundary } from '@mui-internal/test-utils';
+import { RichTreeView } from '@mui/x-tree-view/RichTreeView';
+import { SimpleTreeView } from '@mui/x-tree-view/SimpleTreeView';
+import { TreeItem } from '@mui/x-tree-view/TreeItem';
+
+describe('useTreeViewNodes', () => {
+  const { render } = createRenderer();
+
+  it('should throw an error when two items have the same ID (items prop approach)', function test() {
+    // TODO is this fixed?
+    if (!/jsdom/.test(window.navigator.userAgent)) {
+      // can't catch render errors in the browser for unknown reason
+      // tried try-catch + error boundary + window onError preventDefault
+      this.skip();
+    }
+
+    expect(() =>
+      render(
+        <ErrorBoundary>
+          <RichTreeView
+            items={[
+              { id: '1', label: '1' },
+              { id: '1', label: 'B' },
+            ]}
+          />
+        </ErrorBoundary>,
+      ),
+    ).toErrorDev([
+      'MUI X: The Tree View component requires all items to have a unique `id` property.',
+      'MUI X: The Tree View component requires all items to have a unique `id` property.',
+      'The above error occurred in the <ForwardRef(RichTreeView)> component:',
+    ]);
+  });
+
+  it('should throw an error when two items have the same ID (JSX approach)', function test() {
+    // TODO is this fixed?
+    if (!/jsdom/.test(window.navigator.userAgent)) {
+      // can't catch render errors in the browser for unknown reason
+      // tried try-catch + error boundary + window onError preventDefault
+      this.skip();
+    }
+
+    expect(() =>
+      render(
+        <ErrorBoundary>
+          <SimpleTreeView>
+            <TreeItem nodeId="1" label="A" />
+            <TreeItem nodeId="1" label="B" />
+          </SimpleTreeView>
+        </ErrorBoundary>,
+      ),
+    ).toErrorDev([
+      'MUI X: The Tree View component requires all items to have a unique `id` property.',
+      'MUI X: The Tree View component requires all items to have a unique `id` property.',
+      'The above error occurred in the <ForwardRef(SimpleTreeView)> component:',
+    ]);
+  });
+});

packages/x-tree-view/src/internals/plugins/useTreeViewNodes/useTreeViewNodes.ts

@@ -29,6 +29,7 @@ const updateState = ({
     parentId: string | null,
   ): TreeViewNodeIdAndChildren => {
     const id: string = getItemId ? getItemId(item) : (item as any).id;
+
     if (id == null) {
       throw new Error(
         [
@@ -40,6 +41,16 @@ const updateState = ({
       );
     }
 
+    if (nodeMap[id] != null) {
+      throw new Error(
+        [
+          'MUI X: The Tree View component requires all items to have a unique `id` property.',
+          'Alternatively, you can use the `getItemId` prop to specify a custom id for each item.',
+          `Tow items were provided with the same id in the \`items\` prop: "${id}"`,
+        ].join('\n'),
+      );
+    }
+
     const label = getItemLabel ? getItemLabel(item) : (item as { label: string }).label;
     if (label == null) {
       throw new Error(