fix: use a proxy for the caches export

packages/cache/src/fetchwithcache.test.ts

@@ -2,10 +2,10 @@ import { Buffer } from 'node:buffer'
 import { Readable } from 'node:stream'
 import type { ReadableStream } from 'node:stream/web'
 
-import { describe, test, expect, beforeAll, afterAll } from 'vitest'
+import { describe, test, expect, beforeEach, afterAll } from 'vitest'
 
 import { NetlifyCacheStorage } from './bootstrap/cachestorage.js'
-import type { FetchWithCache } from './fetchwithcache.js'
+import { fetchWithCache } from './fetchwithcache.js'
 import { getMockFetch } from './test/fetch.js'
 import { readAsString, sleep } from './test/util.js'
 import { decodeHeaders } from './test/headers.js'
@@ -17,17 +17,11 @@ const token = 'mock-token'
 
 let originalCaches = globalThis.caches
 
-let fetchWithCache: FetchWithCache
-
-beforeAll(async () => {
+beforeEach(async () => {
   globalThis.caches = new NetlifyCacheStorage({
     base64Encode,
     getContext: () => ({ host, token, url }),
   })
-
-  // Using a dynamic import so that `globalThis.caches` is populated by the
-  // time the polyfill is loaded.
-  fetchWithCache = (await import('./fetchwithcache.js')).fetchWithCache
 })
 
 afterAll(() => {
@@ -183,4 +177,27 @@ describe('`fetchWithCache`', () => {
       expect(mockFetch.requests.length).toBe(4)
     })
   })
+
+  test('Uses the exported `caches` proxy', async () => {
+    const html = '<h1>Hello world</h1>'
+    const mockFetch = getMockFetch({
+      responses: {
+        'https://example.netlify/.netlify/cache/https%3A%2F%2Fnetlify.com%2F': [new Response(html)],
+        'https://netlify.com/': [new Response(html)],
+      },
+    })
+    const resourceURL = 'https://netlify.com'
+    const responseWithCache = await fetchWithCache(resourceURL)
+    expect(await responseWithCache.text()).toBe('<h1>Hello world</h1>')
+
+    // @ts-expect-error
+    delete globalThis.caches
+
+    const responseWithProxy = await fetchWithCache(resourceURL)
+    expect(await responseWithProxy.text()).toBe('<h1>Hello world</h1>')
+
+    mockFetch.restore()
+
+    expect(mockFetch.requests.length).toBe(2)
+  })
 })

packages/cache/src/fetchwithcache.ts

@@ -52,7 +52,7 @@ const isRequestInit = (input: any): input is RequestInit => {
   return false
 }
 
-export type FetchWithCache = {
+type FetchWithCache = {
   (request: string | URL | Request, init?: RequestInit): Promise<Response>
   (request: string | URL | Request, cacheSettings?: CacheOptions): Promise<Response>
   (request: string | URL | Request, init: RequestInit, cacheSettings?: CacheOptions): Promise<Response>

packages/cache/src/main.test.ts

@@ -28,7 +28,7 @@ describe('`caches` export', () => {
       getContext: () => ({ host, token, url }),
     })
 
-    const cache2 = await globalThis.caches.open('cache2')
+    const cache2 = await caches.open('cache2')
     const res2 = await cache2.match('https://netlify.com')
     expect(res2?.status).toBe(200)
     expect(await res2?.text()).toBe(html)

packages/cache/src/polyfill.ts

@@ -1,13 +1,68 @@
-import { NetlifyCacheStorage } from './bootstrap/cachestorage.js'
-
 /**
  * Polyfill for local development environments where `globalThis.caches` is not
- * available. This is a no-op cache, which will automatically work with the
- * real one in production.
+ * available. It's a no-op cache. In production it will use the real one that
+ * has been set up in the environment by the bootstrap layer.
  */
-export const caches =
-  globalThis.caches ??
-  new NetlifyCacheStorage({
-    base64Encode: () => '',
-    getContext: () => null,
-  })
+class NetlifyCacheStorageProxy implements CacheStorage {
+  async delete(name: string): Promise<boolean> {
+    if (globalThis.caches) {
+      return globalThis.caches.delete(name)
+    }
+
+    return false
+  }
+
+  async has(name: string): Promise<boolean> {
+    if (globalThis.caches) {
+      return globalThis.caches.has(name)
+    }
+
+    return false
+  }
+
+  async keys(): Promise<string[]> {
+    if (globalThis.caches) {
+      return globalThis.caches.keys()
+    }
+
+    return []
+  }
+
+  async match(request: RequestInfo, options?: MultiCacheQueryOptions): Promise<Response | undefined> {
+    if (globalThis.caches) {
+      return globalThis.caches.match(request, options)
+    }
+  }
+
+  async open(cacheName: string) {
+    if (globalThis.caches) {
+      return globalThis.caches.open(cacheName)
+    }
+
+    return new NetlifyNoopCache()
+  }
+}
+
+class NetlifyNoopCache implements Cache {
+  async add(_: RequestInfo): Promise<void> {}
+
+  async addAll(_: RequestInfo[]): Promise<void> {}
+
+  async delete(_: RequestInfo): Promise<boolean> {
+    return true
+  }
+
+  async keys(_?: Request): Promise<Array<Request>> {
+    return []
+  }
+
+  async match(_: RequestInfo): Promise<undefined> {}
+
+  async matchAll(_?: RequestInfo): Promise<readonly Response[]> {
+    return []
+  }
+
+  async put(_: RequestInfo | URL | string, __: Response) {}
+}
+
+export const caches = new NetlifyCacheStorageProxy()