Add test to verify that inner caches are excluded from Resume Data Cache

packages/next/src/server/resume-data-cache/cache-store.ts

@@ -8,7 +8,10 @@ import type { CachedFetchValue } from '../response-cache/types'
 /**
  * A generic cache store type that provides a subset of Map functionality
  */
-type CacheStore<T> = Pick<Map<string, T>, 'entries' | 'size' | 'get' | 'set'>
+type CacheStore<T> = Pick<
+  Map<string, T>,
+  'entries' | 'keys' | 'size' | 'get' | 'set'
+>
 
 /**
  * A cache store specifically for fetch cache values

test/e2e/app-dir/use-cache/app/rdc/page.tsx

@@ -0,0 +1,33 @@
+import { connection } from 'next/server'
+import { Suspense } from 'react'
+
+async function outermost(id: string) {
+  'use cache'
+  return id + middle('middle')
+}
+
+async function middle(id: string) {
+  'use cache'
+  return id + innermost('inner')
+}
+
+async function innermost(id: string) {
+  'use cache'
+  return id
+}
+
+async function Dynamic() {
+  await connection()
+  return null
+}
+
+export default async function Page() {
+  await outermost('outer')
+  await innermost('inner')
+
+  return (
+    <Suspense>
+      <Dynamic />
+    </Suspense>
+  )
+}

test/e2e/app-dir/use-cache/use-cache.test.ts

@@ -3,6 +3,10 @@ import { retry, waitFor } from 'next-test-utils'
 import stripAnsi from 'strip-ansi'
 import { format } from 'util'
 import { BrowserInterface } from 'next-webdriver'
+import {
+  createRenderResumeDataCache,
+  RenderResumeDataCache,
+} from 'next/dist/server/resume-data-cache/resume-data-cache'
 
 const GENERIC_RSC_ERROR =
   'An error occurred in the Server Components render. The specific message is omitted in production builds to avoid leaking sensitive details. A digest property is included on this error instance which may provide additional details about the nature of the error.'
@@ -596,6 +600,27 @@ describe('use-cache', () => {
       })
     })
   }
+
+  if (isNextStart && process.env.__NEXT_EXPERIMENTAL_PPR === 'true') {
+    it('should exclude inner caches from the resume data cache (RDC)', async () => {
+      await next.fetch('/rdc')
+
+      const resumeDataCache = extractResumeDataCacheFromPostponedState(
+        JSON.parse(await next.readFile('.next/server/app/rdc.meta')).postponed
+      )
+
+      const cacheKeys = Array.from(resumeDataCache.cache.keys())
+
+      // There should be no cache entry for the "middle" cache function, because
+      // it's only used inside another cache scope ("outer"). Whereas "inner" is
+      // also used inside a prerender scope (the page). Note: We're matching on
+      // the "id" args that are encoded into the respective cache keys.
+      expect(cacheKeys).toMatchObject([
+        expect.stringContaining('["outer"]'),
+        expect.stringContaining('["inner"]'),
+      ])
+    })
+  }
 })
 
 async function getSanitizedLogs(browser: BrowserInterface): Promise<string[]> {
@@ -607,3 +632,14 @@ async function getSanitizedLogs(browser: BrowserInterface): Promise<string[]> {
     )
   )
 }
+
+function extractResumeDataCacheFromPostponedState(
+  state: string
+): RenderResumeDataCache {
+  const postponedStringLengthMatch = state.match(/^([0-9]*):/)![1]
+  const postponedStringLength = parseInt(postponedStringLengthMatch)
+
+  return createRenderResumeDataCache(
+    state.slice(postponedStringLengthMatch.length + postponedStringLength + 1)
+  )
+}