chore: add benchmarks

.github/workflows/benchmarks.yml

@@ -0,0 +1,48 @@
+name: Benchmarks
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'packages/starlight/**'
+      - '!packages/starlight/__tests__/**'
+      - '!packages/starlight/__e2e__/**'
+      - 'package.json'
+      - 'pnpm-lock.yaml'
+      - 'pnpm-workspace.yaml'
+      - '.github/workflows/benchmarks.yml'
+  pull_request:
+    branches: [main]
+    paths:
+      - 'packages/starlight/**'
+      - '!packages/starlight/__tests__/**'
+      - '!packages/starlight/__e2e__/**'
+      - 'package.json'
+      - 'pnpm-lock.yaml'
+      - 'pnpm-workspace.yaml'
+      - '.github/workflows/benchmarks.yml'
+  workflow_dispatch:
+
+concurrency:
+  group: codspeed-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  benchmarks:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      id-token: write
+    steps:
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+      - uses: pnpm/action-setup@0ebf47130e4866e96fce0953f49152a61190b271 # v6.0.9
+      - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
+        with:
+          node-version: 22.23.1
+          cache: pnpm
+      - run: pnpm i --filter @astrojs/starlight
+      - name: Run benchmarks
+        uses: CodSpeedHQ/action@4296e51e7041e24dadb86d1d6e8b9320d223dbe8 # v5.0.3
+        with:
+          mode: simulation
+          run: pnpm --filter @astrojs/starlight bench

.gitignore

@@ -22,3 +22,5 @@ test-results/
 
 # Vercel output
 .vercel
+
+.idea

packages/starlight/.npmignore

@@ -2,6 +2,7 @@
 __coverage__/
 __tests__/
 __e2e__/
+__bench_fn__/
 vitest.*
 playwright.config.ts
 # Astro generates this during tests, but we want to ignore it.

packages/starlight/__bench_fn__/generate-route-data.bench.ts

@@ -0,0 +1,50 @@
+import { bench, describe, vi } from 'vitest';
+import { getRouteDataTestContext } from '../__tests__/test-utils';
+import { generateRouteData } from '../utils/routing/data';
+import { getRouteBySlugParam } from '../utils/routing';
+import { getSidebar } from '../utils/navigation';
+
+const docs = vi.hoisted(() => {
+	const docs: [string, { title: string }][] = [];
+	for (let section = 0; section < 10; section++) {
+		const nesting = Array.from({ length: 7 }, (_, index) => `level-${index + 1}`).join('/');
+		for (let page = 0; page < 100; page++) {
+			docs.push([
+				`reference/section-${section}/${nesting}/page-${page}.md`,
+				{ title: `Page ${section}-${page}` },
+			]);
+		}
+	}
+	return docs;
+});
+
+vi.mock('astro:content', async () =>
+	(await import('../__tests__/test-utils')).mockedAstroContent({ docs })
+);
+
+const slug = 'reference/section-9/level-1/level-2/level-3/level-4/level-5/level-6/level-7/page-99';
+const route = getRouteBySlugParam(slug);
+if (!route) throw new Error('Expected deep benchmark route to exist.');
+
+const context = getRouteDataTestContext({ pathname: `/${slug}/` });
+const props = {
+	...route,
+	headings: Array.from({ length: 30 }, (_, index) => ({
+		depth: 2,
+		slug: `heading-${index}`,
+		text: `Heading ${index}`,
+	})),
+};
+
+// Build intermediate sidebar data once so this models subsequent page generation during a build.
+getSidebar(context.url.pathname, route.locale);
+
+describe('routing', () => {
+	bench('route_data', () => {
+		generateRouteData({ props, context });
+	});
+
+	bench('sidebar', () => {
+		getSidebar(context.url.pathname, route.locale);
+	});
+});

packages/starlight/package.json

@@ -5,6 +5,8 @@
   "scripts": {
     "test": "VITE_CONFIG_NATIVE_IGNORE_WARNING=true vitest",
     "test:coverage": "VITE_CONFIG_NATIVE_IGNORE_WARNING=true vitest run --coverage",
+    "bench": "pnpm bench:functional",
+    "bench:functional": "VITE_CONFIG_NATIVE_IGNORE_WARNING=true vitest bench --run --config vitest.functional.bench.config.ts __bench_fn__/*.bench.ts",
     "test:e2e": "playwright install --with-deps chromium && playwright test",
     "test:e2e:ci": "playwright test"
   },
@@ -59,6 +61,7 @@
   "devDependencies": {
     "@astrojs/markdown-remark": "^7.2.2",
     "@playwright/test": "^1.61.1",
+    "@codspeed/vitest-plugin": "^5.7.1",
     "@types/node": "^22.19.17",
     "@vitest/coverage-v8": "^4.1.5",
     "astro": "^7.1.6",

packages/starlight/vitest.functional.bench.config.ts

@@ -0,0 +1,24 @@
+import codspeedPlugin from '@codspeed/vitest-plugin';
+import { defineVitestConfig } from './__tests__/test-config';
+
+const testConfig = await defineVitestConfig({
+	title: 'Starlight benchmarks',
+	sidebar: [{ label: 'Reference', items: [{ autogenerate: { directory: 'reference' } }] }],
+});
+
+export default async (env: Parameters<typeof testConfig>[0]) => {
+	const config = await testConfig(env);
+	return {
+		...config,
+		plugins: [...(config.plugins ?? []), codspeedPlugin()],
+		test: {
+			...config.test,
+			// The shared serializer path is not resolvable from this root benchmark config.
+			snapshotSerializers: [],
+			benchmark: {
+				include: ['__bench_fn__/*.bench.ts'],
+			},
+			fileParallelism: false,
+		},
+	};
+};