chore: try out codspeed for CI benchmarking

.github/workflows/codspeed.yml

@@ -0,0 +1,27 @@
+name: codspeed-benchmarks
+
+on:
+  pull_request:
+    branches:
+      - "main"
+  # `workflow_dispatch` allows CodSpeed to trigger backtest
+  # performance analysis in order to generate initial data.
+  workflow_dispatch:
+
+jobs:
+  benchmarks:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: pnpm/action-setup@v4
+      - uses: actions/setup-node@v4
+        with:
+          registry-url: 'https://registry.npmjs.org'
+          node-version: '22.x'
+          cache: pnpm
+      - run: pnpm install
+      - name: Run benchmarks
+        uses: CodSpeedHQ/action@v2
+        with:
+          token: ${{ secrets.CODSPEED_TOKEN }}
+          run: pnpm bench

package.json

@@ -13,10 +13,12 @@
     "lint": "tsc && biome check && pnpm -s dlx [email protected] lint",
     "format": "biome check --fix --unsafe",
     "test": "vitest run --coverage",
+    "bench": "vitest bench",
     "prepublishOnly": "tsc && biome check --fix && pnpm -s build"
   },
   "devDependencies": {
     "@biomejs/biome": "^1.8.3",
+    "@codspeed/vitest-plugin": "^3.1.0",
     "@vitest/coverage-v8": "1.6.0",
     "tsup": "^8.1.0",
     "typescript": "^5.5.2",

vitest.config.ts

@@ -1,9 +1,13 @@
-import { defineConfig } from 'vitest/config'
+import codspeed from '@codspeed/vitest-plugin'
+import { defineConfig, UserConfig } from 'vitest/config'
+
+// FIXME: vitest doesn‘t provide the Plugin type???
+type Plugin = Extract<UserConfig['plugins'], any[]>[number]
 
 const resolve = (specifier: string) =>
   new URL(import.meta.resolve(specifier)).pathname
 
-export default defineConfig({
+export default defineConfig(({ mode }) => ({
   test: {
     globals: true,
     coverage: {
@@ -16,4 +20,7 @@ export default defineConfig({
       radashi: resolve('./src/mod.js'),
     },
   },
-})
+  plugins: [
+    mode === 'benchmark' && process.env.CI ? (codspeed() as Plugin) : [],
+  ],
+}))