faster 404 for missing static assets (#25124)

tests/rendering/static-assets.js

@@ -0,0 +1,66 @@
+import fs from 'fs'
+import path from 'path'
+
+import { expect } from '@jest/globals'
+
+import { SURROGATE_ENUMS } from '../../middleware/set-fastly-surrogate-key.js'
+import { get } from '../helpers/supertest.js'
+
+function getNextStaticAsset(directory) {
+  const root = path.join('.next', 'static', directory)
+  const files = fs.readdirSync(root)
+  if (!files.length) throw new Error(`Can't find any files in ${root}`)
+  return path.join(root, files[0])
+}
+
+function checkCachingHeaders(res, defaultSurrogateKey = false) {
+  expect(res.headers['set-cookie']).toBeUndefined()
+  expect(res.headers['cache-control']).toContain('public')
+  const maxAgeSeconds = parseInt(res.header['cache-control'].match(/max-age=(\d+)/)[1], 10)
+  // Let's not be too specific in the tests, just as long as it's testing
+  // that it's a reasonably large number of seconds.
+  expect(maxAgeSeconds).toBeGreaterThanOrEqual(60 * 60)
+  // Because it doesn't have have a unique URL
+  expect(res.headers['surrogate-key']).toBe(
+    defaultSurrogateKey ? SURROGATE_ENUMS.DEFAULT : SURROGATE_ENUMS.MANUAL
+  )
+}
+describe('static assets', () => {
+  it('should serve /assets/cb-* with optimal headers', async () => {
+    const res = await get('/assets/cb-1234/images/site/logo.png')
+    expect(res.statusCode).toBe(200)
+    checkCachingHeaders(res)
+  })
+
+  it('should serve /assets/ with optimal headers', async () => {
+    const res = await get('/assets/images/site/logo.png')
+    expect(res.statusCode).toBe(200)
+    checkCachingHeaders(res, true)
+  })
+
+  it('should serve /_next/static/ with optimal headers', async () => {
+    // This picks the first one found. We just need it to be anything
+    // that actually resolves.
+    const filePath = getNextStaticAsset('css')
+    const asURL = '/' + filePath.replace('.next', '_next').split(path.sep).join('/')
+    const res = await get(asURL)
+    expect(res.statusCode).toBe(200)
+    checkCachingHeaders(res)
+  })
+
+  it('should 404 on /assets/cb-* with plain text', async () => {
+    const res = await get('/assets/cb-1234/never/heard/of.png')
+    expect(res.statusCode).toBe(404)
+    expect(res.header['content-type']).toContain('text/plain')
+  })
+  it('should 404 on /assets/ with plain text', async () => {
+    const res = await get('/assets/never/heard/of.png')
+    expect(res.statusCode).toBe(404)
+    expect(res.header['content-type']).toContain('text/plain')
+  })
+  it('should 404 on /_next/static/ with plain text', async () => {
+    const res = await get('/_next/static/never/heard/of.css')
+    expect(res.statusCode).toBe(404)
+    expect(res.header['content-type']).toContain('text/plain')
+  })
+})