Ensure beforeFiles client-side resolving handles dynamic routes (#36317)

This fixes resolving `beforeFiles` rewrites with `next/link` as previously we weren't resolving the destination to a dynamic route since the resolving was being marked as finished when it shouldn't be during `beforeFiles`. 

## Bug

- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [x] Errors have helpful link attached, see `contributing.md`

Fixes: #35402

packages/next/shared/lib/router/utils/resolve-rewrites.ts

@@ -106,7 +106,7 @@ export default function resolveRewrites(
   for (let i = 0; i < rewrites.beforeFiles.length; i++) {
     // we don't end after match in beforeFiles to allow
     // continuing through all beforeFiles rewrites
-    finished = handleRewrite(rewrites.beforeFiles[i]) || false
+    handleRewrite(rewrites.beforeFiles[i])
   }
   matchedPage = pages.includes(fsPathname)
 

test/integration/custom-routes/next.config.js

@@ -224,6 +224,10 @@ module.exports = {
           source: '/overridden',
           destination: 'https://vercel.com',
         },
+        {
+          source: '/nfl/:path*',
+          destination: '/_sport/nfl/:path*',
+        },
       ],
     }
   },

test/integration/custom-routes/pages/_sport/[slug]/index.js

@@ -0,0 +1,13 @@
+import { useRouter } from 'next/router'
+
+export default function Page() {
+  const router = useRouter()
+  return (
+    <>
+      <p>/_sport/[slug]</p>
+      <p id="query">{JSON.stringify(router.query)}</p>
+      <p id="as-path">{router.asPath}</p>
+      <p id="pathname">{router.pathname}</p>
+    </>
+  )
+}

test/integration/custom-routes/pages/_sport/[slug]/test.js

@@ -0,0 +1,13 @@
+import { useRouter } from 'next/router'
+
+export default function Page() {
+  const router = useRouter()
+  return (
+    <>
+      <p>/_sport/[slug]/test</p>
+      <p id="query">{JSON.stringify(router.query)}</p>
+      <p id="as-path">{router.asPath}</p>
+      <p id="pathname">{router.pathname}</p>
+    </>
+  )
+}

test/integration/custom-routes/pages/nav.js

@@ -44,6 +44,15 @@ const Page = () => (
       <a id="to-before-files-overridden">to /overridden</a>
     </Link>
     <br />
+    <Link href="/nfl">
+      <a id="to-before-files-dynamic">to /nfl</a>
+    </Link>
+    <br />
+    <Link href="/nfl/test">
+      <a id="to-before-files-dynamic-again">to /nfl/test</a>
+    </Link>
+    <br />
   </>
 )
+
 export default Page

test/integration/custom-routes/test/index.test.js

@@ -99,6 +99,58 @@ const runTests = (isDev = false) => {
     )
   })
 
+  it('should handle beforeFiles rewrite to dynamic route correctly', async () => {
+    const res = await fetchViaHTTP(appPort, '/nfl')
+    const html = await res.text()
+
+    if (res.status !== 200) {
+      console.error('Invalid response', html)
+    }
+    expect(res.status).toBe(200)
+    expect(html).toContain('/_sport/[slug]')
+
+    const browser = await webdriver(appPort, '/nav')
+    await browser.eval('window.beforeNav = 1')
+    await browser.elementByCss('#to-before-files-dynamic').click()
+    await check(
+      () => browser.eval('document.documentElement.innerHTML'),
+      /_sport\/\[slug\]/
+    )
+    expect(JSON.parse(await browser.elementByCss('#query').text())).toEqual({
+      slug: 'nfl',
+    })
+    expect(await browser.elementByCss('#pathname').text()).toBe(
+      '/_sport/[slug]'
+    )
+    expect(await browser.eval('window.beforeNav')).toBe(1)
+  })
+
+  it('should handle beforeFiles rewrite to partly dynamic route correctly', async () => {
+    const res = await fetchViaHTTP(appPort, '/nfl')
+    const html = await res.text()
+
+    if (res.status !== 200) {
+      console.error('Invalid response', html)
+    }
+    expect(res.status).toBe(200)
+    expect(html).toContain('/_sport/[slug]')
+
+    const browser = await webdriver(appPort, '/nav')
+    await browser.eval('window.beforeNav = 1')
+    await browser.elementByCss('#to-before-files-dynamic-again').click()
+    await check(
+      () => browser.eval('document.documentElement.innerHTML'),
+      /_sport\/\[slug\]\/test/
+    )
+    expect(JSON.parse(await browser.elementByCss('#query').text())).toEqual({
+      slug: 'nfl',
+    })
+    expect(await browser.elementByCss('#pathname').text()).toBe(
+      '/_sport/[slug]/test'
+    )
+    expect(await browser.eval('window.beforeNav')).toBe(1)
+  })
+
   it('should support long URLs for rewrites', async () => {
     const res = await fetchViaHTTP(
       appPort,
@@ -1720,6 +1772,13 @@ const runTests = (isDev = false) => {
               regex: normalizeRegEx('^\\/overridden(?:\\/)?$'),
               source: '/overridden',
             },
+            {
+              destination: '/_sport/nfl/:path*',
+              regex: normalizeRegEx(
+                '^\\/nfl(?:\\/((?:[^\\/]+?)(?:\\/(?:[^\\/]+?))*))?(?:\\/)?$'
+              ),
+              source: '/nfl/:path*',
+            },
           ],
           afterFiles: [
             {
@@ -1973,6 +2032,22 @@ const runTests = (isDev = false) => {
           fallback: [],
         },
         dynamicRoutes: [
+          {
+            namedRegex: '^/_sport/(?<slug>[^/]+?)(?:/)?$',
+            page: '/_sport/[slug]',
+            regex: normalizeRegEx('^\\/_sport\\/([^\\/]+?)(?:\\/)?$'),
+            routeKeys: {
+              slug: 'slug',
+            },
+          },
+          {
+            namedRegex: '^/_sport/(?<slug>[^/]+?)/test(?:/)?$',
+            page: '/_sport/[slug]/test',
+            regex: normalizeRegEx('^\\/_sport\\/([^\\/]+?)\\/test(?:\\/)?$'),
+            routeKeys: {
+              slug: 'slug',
+            },
+          },
           {
             namedRegex: '^/another/(?<id>[^/]+?)(?:/)?$',
             page: '/another/[id]',