fix(react-router): a lazy route follows a barrel that re-exports an import

CHANGELOG.md

@@ -137,6 +137,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 - In JavaScript and TypeScript, a module loaded with `require('./x').default` or `const { default: X } = require('./x')` now links to its default export when it is written as an ES module: bitwarden's desktop app loads `export default class OsBiometricsServiceMac` this way before calling `new OsBiometricsServiceMac(…)`, and React Native's own libraries load many of their modules like this. Before, `.default` was looked up only as an export named `default`, which `export default` is not, so the `new` and the calls made through it linked to nothing, to the local variable holding the module, or to a method of the same name somewhere else. A Svelte component loaded this way and created with `new App({ target })` now links to the component. A CommonJS module that sets `exports.default` itself, or both `module.exports` and `module.exports.default` as fastify does, still links to what it sets, and one that sets no `default` still links to nothing. Re-index JavaScript and TypeScript projects after upgrading.
 - A React Router route that lazily loads a folder, like `lazy: () => import('@/pages/invocation_page')`, now links to the page the folder's `index.ts` passes on, whether it writes `export * from './invocation_page'`, `export { default } from './page'` or `export { Page as Component } from './page'`, even through another `index.ts`. A route module that names its page with `export { Page as Component }` links to it as well, and so does a page loaded with `lazy(() => import(…))` through such an `index.ts`. Before, these routes linked to nothing, so their pages had no route leading to them. Re-index React projects after upgrading.
 - A React Router route whose `lazy` loader picks its page from the module it loads now links to that page: `lazy: async () => { const { TestTab } = await import('./tabs'); return { Component: TestTab }; }`, `const { default: Component } = await import('./pages/Login')`, `import('./reports').then((m) => ({ Component: m.ReportList }))`, `({ Component: (await import('./reports')).ReportPage })`, React Router 7's `lazy: { Component: async () => (await import('./show')).Show }`, and a page the loader shows inside a guard, like `element: <AgeGate><FireworksPage /></AgeGate>`. Before, such a route linked to the module's default export, else its `Component` export, which is a different page or none at all, as with luci-go's tabs loaded from a folder that forwards them. A loader written as a method, `async lazy() { … }`, is now read too, so its route is no longer missing, and a loader that hands React Router only a `loader` no longer makes the module's default export the route's page or the layout of the routes inside it. Re-index React projects after upgrading.
+- A React Router route, or a page loaded with `lazy(() => import(…))`, now links to its page when the folder it loads passes the page on through an import of its own, like `import { UserLayout } from './UserLayout'; export { UserLayout }` or `import Login from './Login'; export default Login`. Before, the folder's `index.ts` was searched for a page declared in it, which it doesn't have, so the route linked nothing. A default export that wraps the page in a call, like `export default withAuth(Page)`, still links neither the wrapper nor a guess. Re-index React projects after upgrading.
 - In JavaScript and TypeScript, an import written `import { default as AppRoot } from './routes/app/root'`, as in bulletproof-react's router, now counts as the module's default import, the same as `import AppRoot from './routes/app/root'`. Before, it was read as an import of an export named `default`, which no module has, so a call, a route or a JSX attribute that used `AppRoot` was matched by its name alone: it could link to another file's `AppRoot`, or to nothing when the default export has a name of its own. Svelte, Vue and Astro script blocks are read the same way.
 - In React, a component's JSX no longer links it to a class or component that only shares a name with one of its type arguments or with a variable of its own. A type in angle brackets, like `Document` in `<PaginatedList<Document> items={…} />`, `User` in `useState<User>()` or `Entry` in a generic `<Entry extends BaseEntity>(…) =>` component, is no longer read as a tag. A tag naming a variable or parameter the component sets itself, like `<Content>` after `const Content = isDropdown ? DropdownMenu.SubContent : ContextMenu.SubContent` or `<Widget>` in `widgets.map((Widget) => <Widget />)`, now links to nothing, unless the component declares a component of that name inside itself. Before, these linked to an unrelated class or component elsewhere in the repository: outline's document lists showed up among the callers of its `Document` model class, and its menus among the callers of the command bar's `Content`, so `codegraph_explore`, callers and impact followed renders that never happen. Re-index React projects after upgrading.
 - In JavaScript and TypeScript, a name imported from a package your `package.json` lists no longer links to a project symbol that only shares its name when `tsconfig.json` or `jsconfig.json` has a catch-all path alias, like `"*": ["./typings/*"]` or `"*": ["src/*", "node_modules/*"]`, or an alias that points the package at a file in `node_modules`, like `"lit/decorators": ["./node_modules/lit/decorators.js"]`. Such an alias made every package look like part of the project, so `import { Typography } from '@mui/material'` was linked to the project's own `Typography` and every lit `@property()` decorator to an unrelated class's `property` field, and `codegraph callers`, impact and `codegraph affected` listed code that never used them. An import the alias does map to a file of your project, like a `.d.ts` you keep for an untyped package or `components/Button` through `"*": ["src/*"]`, links as before. Re-index affected projects after upgrading.

__tests__/react-router-barrel-imports.test.ts

@@ -0,0 +1,229 @@
+/**
+ * A lazily loaded module that passes on a page it imports
+ * (Arshia76/DigiShop.Frontend): `src/layout/index.ts` does `import {
+ * UserLayout } from './UserLayout'; export { UserLayout }`, so
+ * `lazy: async () => { const { UserLayout } = await import('@/layout');
+ * return { Component: UserLayout }; }` renders `UserLayout`. The barrel
+ * declares no `UserLayout` of its own, and before, its export clause was read
+ * as naming one, so the route linked nothing.
+ */
+import { describe, it, expect, afterAll, afterEach, beforeAll } from 'vitest';
+import * as fs from 'fs';
+import * as os from 'os';
+import * as path from 'path';
+import { CodeGraph } from '../src';
+
+let root = '';
+let cg: CodeGraph;
+
+const PKG = JSON.stringify({ name: 'shop', private: true, dependencies: { react: '^18', 'react-router': '^7', '@mui/material': '^6' } });
+const TSCONFIG = JSON.stringify({ compilerOptions: { baseUrl: '.', paths: { '@/*': ['./src/*'] } } });
+
+beforeAll(async () => {
+  root = fs.mkdtempSync(path.join(os.tmpdir(), 'cg-rr-barrel-imports-'));
+  const files: Record<string, string> = {
+    'package.json': PKG,
+    'tsconfig.json': TSCONFIG,
+    'src/router.tsx': `import { lazy } from 'react';
+import { createBrowserRouter } from 'react-router';
+
+const Help = lazy(() => import('@/help'));
+
+export const router = createBrowserRouter([
+  {
+    path: '/',
+    lazy: async () => {
+      const { UserLayout } = await import('@/layout');
+      return { Component: UserLayout };
+    },
+    children: [
+      {
+        index: true,
+        lazy: async () => {
+          const { HomePage } = await import('@/pages');
+          return { Component: HomePage };
+        },
+      },
+      { path: 'login', lazy: () => import('@/auth/login') },
+      { path: 'settings', lazy: () => import('@/settings') },
+      { path: 'help', element: <Help /> },
+      {
+        path: 'tabs',
+        lazy: async () => {
+          const { Tabs } = await import('@/tabs');
+          return { Component: Tabs };
+        },
+      },
+      {
+        path: 'button',
+        lazy: async () => {
+          const { Button } = await import('@/ui');
+          return { Component: Button };
+        },
+      },
+      { path: 'account', lazy: () => import('@/account') },
+    ],
+  },
+  {
+    path: '/admin',
+    lazy: async () => {
+      const { AdminLayout } = await import('@/layout');
+      return { Component: AdminLayout };
+    },
+  },
+]);
+`,
+    // DigiShop's barrel: imports, then one export clause, no semicolons.
+    'src/layout/index.ts': `import { AdminLayout } from './AdminLayout'
+import { UserLayout } from './UserLayout'
+
+export { AdminLayout, UserLayout }
+`,
+    'src/layout/AdminLayout.tsx': 'export function AdminLayout() {\n  return null;\n}\n',
+    'src/layout/UserLayout.tsx': 'export const UserLayout = () => null;\n',
+    // A barrel that imports from another barrel.
+    'src/pages/index.ts': "import { HomePage } from './home';\n\nexport { HomePage };\n",
+    'src/pages/home/index.ts': "export * from './HomePage';\n",
+    'src/pages/home/HomePage.tsx': 'export function HomePage() {\n  return null;\n}\n',
+    // The default export is an imported binding.
+    'src/auth/login/index.ts': "import Login from './Login';\n\nexport default Login;\n",
+    'src/auth/login/Login.tsx': 'export default function Login() {\n  return null;\n}\n',
+    // Renamed to the name React Router reads.
+    'src/settings/index.ts': "import { SettingsPage } from './SettingsPage';\n\nexport { SettingsPage as Component };\n",
+    'src/settings/SettingsPage.tsx': 'export function SettingsPage() {\n  return null;\n}\n',
+    // `React.lazy` reads the default, here an imported binding renamed to it.
+    'src/help/index.ts': "import HelpPage from './HelpPage';\n\nexport { HelpPage as default };\n",
+    'src/help/HelpPage.tsx': 'export default function HelpPage() {\n  return null;\n}\n',
+    // A namespace object is no component.
+    'src/tabs/index.ts': "import * as Tabs from './tabs';\n\nexport { Tabs };\n",
+    'src/tabs/tabs.tsx': 'export function First() {\n  return null;\n}\n',
+    // A package's component is not the project's to link.
+    'src/ui/index.ts': "import { Button } from '@mui/material';\n\nexport { Button };\n",
+    // The default export is a call: no binding the module imports is the page.
+    'src/account/index.ts': "import withAuth from '@/hoc/withAuth';\nimport { AccountPage } from './AccountPage';\n\nexport default withAuth(AccountPage);\n",
+    'src/account/AccountPage.tsx': 'export function AccountPage() {\n  return null;\n}\n',
+    'src/hoc/withAuth.ts': 'export default function withAuth(Component: unknown) {\n  return Component;\n}\n',
+  };
+  for (const [rel, content] of Object.entries(files)) {
+    fs.mkdirSync(path.dirname(path.join(root, rel)), { recursive: true });
+    fs.writeFileSync(path.join(root, rel), content);
+  }
+  cg = await CodeGraph.init(root, { index: true });
+}, 60_000);
+
+afterAll(() => {
+  cg?.close();
+  if (root) fs.rmSync(root, { recursive: true, force: true });
+});
+
+/** What a route's `references` edges reach, as `name@file`: what it renders, or the layouts around it. */
+const bindings = (routeName: string, layout: boolean): string[] => {
+  const route = cg.getNodesByKind('route').find((r) => r.name === routeName);
+  if (!route) return [`no route ${routeName}`];
+  return cg.getOutgoingEdges(route.id)
+    .filter((e) => e.kind === 'references' && Boolean((e.metadata as Record<string, unknown> | undefined)?.layout) === layout)
+    .map((e) => cg.getNode(e.target)!)
+    .map((n) => `${n.name}@${n.filePath}`);
+};
+const renders = (routeName: string): string[] => bindings(routeName, false);
+
+describe('a lazily loaded module that passes on a page it imports', () => {
+  it('renders the page an export clause of imports passes on', () => {
+    expect(renders('/admin')).toEqual(['AdminLayout@src/layout/AdminLayout.tsx']);
+    expect(bindings('/login', true)).toEqual(['UserLayout@src/layout/UserLayout.tsx']);
+  });
+
+  it('follows the import to another barrel', () => {
+    expect(renders('/')).toEqual(['HomePage@src/pages/home/HomePage.tsx']);
+  });
+
+  it('follows a default export that is an imported binding', () => {
+    expect(renders('/login')).toEqual(['Login@src/auth/login/Login.tsx']);
+  });
+
+  it('follows an imported page the module renames to Component', () => {
+    expect(renders('/settings')).toEqual(['SettingsPage@src/settings/SettingsPage.tsx']);
+  });
+
+  it('follows the default a React.lazy value loads', () => {
+    expect(renders('/help')).toEqual(['HelpPage@src/help/HelpPage.tsx']);
+  });
+
+  it('links nothing for a namespace or a package it passes on', () => {
+    expect(renders('/tabs')).toEqual([]);
+    expect(renders('/button')).toEqual([]);
+  });
+
+  it('links no wrapper a default export calls', () => {
+    expect(renders('/account')).toEqual([]);
+  });
+});
+
+describe('sync, for a module that passes on a page it imports', () => {
+  type Files = Record<string, string>;
+  const ROUTER: Files = {
+    'package.json': PKG,
+    'tsconfig.json': TSCONFIG,
+    'src/router.tsx': `import { createBrowserRouter } from 'react-router';
+
+export const router = createBrowserRouter([
+  { path: '/login', lazy: () => import('@/auth/login') },
+]);
+`,
+    'src/auth/login/index.ts': "import Login from './Login';\n\nexport default Login;\n",
+  };
+  const PAGE: Files = { 'src/auth/login/Login.tsx': 'export default function Login() {\n  return null;\n}\n' };
+
+  let dirs: string[] = [];
+  let graphs: CodeGraph[] = [];
+  afterEach(() => {
+    for (const graph of graphs) graph.close();
+    for (const dir of dirs) fs.rmSync(dir, { recursive: true, force: true });
+    graphs = [];
+    dirs = [];
+  });
+
+  const write = (dir: string, files: Files): void => {
+    for (const [rel, content] of Object.entries(files)) {
+      fs.mkdirSync(path.dirname(path.join(dir, rel)), { recursive: true });
+      fs.writeFileSync(path.join(dir, rel), content);
+    }
+  };
+  /** A project of `files`, indexed from scratch in a folder of its own. */
+  const indexed = async (files: Files): Promise<{ dir: string; graph: CodeGraph }> => {
+    const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'cg-rr-barrel-imports-sync-'));
+    dirs.push(dir);
+    write(dir, files);
+    const graph = await CodeGraph.init(dir, { index: true });
+    graphs.push(graph);
+    return { dir, graph };
+  };
+  /** Each route's `references` edges, as `name@file`. */
+  const routeLinks = (graph: CodeGraph): Record<string, string[]> => Object.fromEntries(
+    graph.getNodesByKind('route').map((route) => [route.name, graph.getOutgoingEdges(route.id)
+      .filter((e) => e.kind === 'references')
+      .map((e) => graph.getNode(e.target)!)
+      .map((n) => `${n.name}@${n.filePath}`)
+      .sort()])
+  );
+
+  it('links the page once the module it imports appears', async () => {
+    const { dir, graph } = await indexed(ROUTER);
+    expect(routeLinks(graph)).toEqual({ '/login': [] });
+    write(dir, PAGE);
+    expect((await graph.sync()).filesAdded).toBe(1);
+    expect(routeLinks(graph)).toEqual({ '/login': ['Login@src/auth/login/Login.tsx'] });
+    expect(routeLinks((await indexed({ ...ROUTER, ...PAGE })).graph)).toEqual({ '/login': ['Login@src/auth/login/Login.tsx'] });
+  }, 60_000);
+
+  it('follows the imported page when its default export moves to another component', async () => {
+    const { dir, graph } = await indexed({ ...ROUTER, ...PAGE });
+    expect(routeLinks(graph)).toEqual({ '/login': ['Login@src/auth/login/Login.tsx'] });
+    // The old component stays, so the route's edge would follow it through the re-index.
+    const edit = { 'src/auth/login/Login.tsx': 'export function Login() {\n  return null;\n}\n\nexport default function SignIn() {\n  return null;\n}\n' };
+    write(dir, edit);
+    await graph.sync();
+    expect(routeLinks(graph)).toEqual({ '/login': ['SignIn@src/auth/login/Login.tsx'] });
+    expect(routeLinks((await indexed({ ...ROUTER, ...edit })).graph)).toEqual({ '/login': ['SignIn@src/auth/login/Login.tsx'] });
+  }, 60_000);
+});