Add a test case to avoid regression on sequential function calling

unstubbable · unstubbable · commit a2d38ee17bd9 · 2025-10-02T11:46:32.000+02:00
After moving the test case for the parent handling to a route that does
not have dynamic params, we now need this additional case to ensure that
the sequential calling of cached `generateMetadata`/`generateViewport`
functions is indeed required to avoid a timeout error.
diff --git a/test/e2e/app-dir/use-cache/app/(partially-static)/generate-metadata-resume/canonical/[slug]/layout.tsx b/test/e2e/app-dir/use-cache/app/(partially-static)/generate-metadata-resume/canonical/[slug]/layout.tsx
@@ -0,0 +1,24 @@
+import { Metadata, ResolvingMetadata } from 'next'
+
+export async function generateMetadata(
+  _: { params: Promise<{ slug: string }> },
+  parent: ResolvingMetadata
+): Promise<Metadata> {
+  'use cache'
+
+  // We're not reading params here, but we do define a canonical URL, which
+  // leads to the pathname being read under the hood. This should make the
+  // function dynamic when prerendering the fallback shell, and not lead to a
+  // timeout error.
+
+  const { metadataBase } = await parent
+
+  return {
+    // We can not return a URL instance from a `'use cache'` function.
+    metadataBase: metadataBase?.replace('/foo', '/bar'),
+  }
+}
+
+export default function Layout({ children }: { children: React.ReactNode }) {
+  return <>{children}</>
+}
diff --git a/test/e2e/app-dir/use-cache/app/(partially-static)/generate-metadata-resume/canonical/[slug]/page.tsx b/test/e2e/app-dir/use-cache/app/(partially-static)/generate-metadata-resume/canonical/[slug]/page.tsx
@@ -0,0 +1,36 @@
+import { Metadata, ResolvingMetadata } from 'next'
+import { connection } from 'next/server'
+import { Suspense } from 'react'
+
+export async function generateMetadata(
+  _: { params: Promise<{ slug: string }> },
+  parent: ResolvingMetadata
+): Promise<Metadata> {
+  'use cache'
+
+  // We're not reading params here, but we do define a canonical URL, which
+  // leads to the pathname being read under the hood. This should make the
+  // function dynamic when prerendering the fallback shell, and not lead to a
+  // timeout error.
+
+  const { metadataBase } = await parent
+
+  return {
+    metadataBase: metadataBase?.replace('/bar', '/baz'),
+    alternates: { canonical: '/qux' },
+  }
+}
+
+export default function Page() {
+  return (
+    <Suspense fallback={<p>Loading...</p>}>
+      <Dynamic />
+    </Suspense>
+  )
+}
+
+async function Dynamic() {
+  await connection()
+
+  return <p>Dynamic</p>
+}
diff --git a/test/e2e/app-dir/use-cache/use-cache.test.ts b/test/e2e/app-dir/use-cache/use-cache.test.ts
@@ -1171,8 +1171,9 @@ describe('use-cache', () => {
     it('can serialize parent metadata as generateMetadata argument', async () => {
       const browser = await next.browser('/generate-metadata-resume/nested')
 
+      // The metadata must be in the head if it was prerendered.
       const canonicalUrl = await browser
-        .elementByCss('link[rel="canonical"]')
+        .elementByCss('head link[rel="canonical"]', { state: 'attached' })
         .getAttribute('href')
 
       expect(canonicalUrl).toBe('https://example.com/baz/qux')
@@ -1181,6 +1182,35 @@ describe('use-cache', () => {
       await assertNoErrorToast(browser)
     })
 
+    it('makes a cached generateMetadata function that implicitly depends on params dynamic during prerendering', async () => {
+      // First load the page with JavaScript disabled, to ensure that no
+      // generateMetadata result was included in the prerendered shell.
+      let browser = await next.browser(
+        '/generate-metadata-resume/canonical/foo',
+        { disableJavaScript: true }
+      )
+
+      // The metadata would be in the head if it was prerendered.
+      expect(
+        await browser
+          .elementByCss('head', { state: 'attached' })
+          .hasElementByCss('link[rel="canonical"]')
+      ).toBe(false)
+
+      // However, it should have been added to the body during the resume.
+      expect(
+        await browser.elementByCss('link[rel="canonical"]').getAttribute('href')
+      ).toBe('https://example.com/baz/qux')
+
+      await browser.close()
+
+      // Load the page again, now with JavaScript enabled.
+      browser = await next.browser('/generate-metadata-resume/canonical/foo')
+
+      // There should be no timeout error.
+      await assertNoErrorToast(browser)
+    })
+
     it('makes a cached generateMetadata function that reads params dynamic during prerendering', async () => {
       // First load the page with JavaScript disabled, to ensure that no
       // generateMetadata result was included in the prerendered shell.
