Support trailingSlash in middleware SSR (#34544)

## Bug

Fixes #34527 

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

packages/next/server/next-server.ts

@@ -8,6 +8,7 @@ import type { ParsedNextUrl } from '../shared/lib/router/utils/parse-next-url'
 import type { PrerenderManifest } from '../build'
 import type { Rewrite } from '../lib/load-custom-routes'
 import type { BaseNextRequest, BaseNextResponse } from './base-http'
+import type { PagesManifest } from '../build/webpack/plugins/pages-manifest-plugin'
 
 import { execOnce } from '../shared/lib/utils'
 import {
@@ -34,7 +35,6 @@ import {
   CLIENT_PUBLIC_FILES_PATH,
   SERVERLESS_DIRECTORY,
 } from '../shared/lib/constants'
-import { PagesManifest } from '../build/webpack/plugins/pages-manifest-plugin'
 import { recursiveReadDirSync } from './lib/recursive-readdir-sync'
 import { format as formatUrl, UrlWithParsedQuery } from 'url'
 import compression from 'next/dist/compiled/compression'
@@ -73,6 +73,7 @@ import { loadEnvConfig } from '@next/env'
 import { getCustomRoute } from './server-route-utils'
 import { urlQueryToSearchParams } from '../shared/lib/router/utils/querystring'
 import ResponseCache from '../server/response-cache'
+import { removePathTrailingSlash } from '../client/normalize-trailing-slash'
 import { clonableBodyForRequest } from './body-streams'
 
 export * from './base-server'
@@ -1030,7 +1031,8 @@ export default class NextNodeServer extends BaseServer {
           },
         })
 
-        if (!this.middleware?.some((m) => m.match(parsedUrl.pathname))) {
+        const normalizedPathname = removePathTrailingSlash(parsedUrl.pathname)
+        if (!this.middleware?.some((m) => m.match(normalizedPathname))) {
           return { finished: false }
         }
 
@@ -1212,6 +1214,9 @@ export default class NextNodeServer extends BaseServer {
     onWarning?: (warning: Error) => void
   }): Promise<FetchEventResult | null> {
     this.middlewareBetaWarning()
+    const normalizedPathname = removePathTrailingSlash(
+      params.parsedUrl.pathname
+    )
 
     // For middleware to "fetch" we must always provide an absolute URL
     const url = getRequestMeta(params.request, '__NEXT_INIT_URL')!
@@ -1222,11 +1227,11 @@ export default class NextNodeServer extends BaseServer {
     }
 
     const page: { name?: string; params?: { [key: string]: string } } = {}
-    if (await this.hasPage(params.parsedUrl.pathname)) {
+    if (await this.hasPage(normalizedPathname)) {
       page.name = params.parsedUrl.pathname
     } else if (this.dynamicRoutes) {
       for (const dynamicRoute of this.dynamicRoutes) {
-        const matchParams = dynamicRoute.match(params.parsedUrl.pathname)
+        const matchParams = dynamicRoute.match(normalizedPathname)
         if (matchParams) {
           page.name = dynamicRoute.page
           page.params = matchParams
@@ -1244,7 +1249,7 @@ export default class NextNodeServer extends BaseServer {
         : undefined
 
     for (const middleware of this.middleware || []) {
-      if (middleware.match(params.parsedUrl.pathname)) {
+      if (middleware.match(normalizedPathname)) {
         if (!(await this.hasMiddleware(middleware.page, middleware.ssr))) {
           console.warn(`The Edge Function for ${middleware.page} was not found`)
           continue

test/production/react-18-streaming-ssr/index.test.ts

@@ -1,8 +1,8 @@
 import { createNext } from 'e2e-utils'
 import { NextInstance } from 'test/lib/next-modes/base'
-import { renderViaHTTP } from 'next-test-utils'
+import { fetchViaHTTP, renderViaHTTP } from 'next-test-utils'
 
-describe('react-18-streaming-ssr in minimal mode', () => {
+describe('react 18 streaming SSR in minimal mode', () => {
   let next: NextInstance
 
   beforeAll(async () => {
@@ -27,10 +27,7 @@ describe('react-18-streaming-ssr in minimal mode', () => {
         react: '18.0.0-rc.0',
         'react-dom': '18.0.0-rc.0',
       },
-      skipStart: true,
     })
-
-    await next.start()
   })
   afterAll(() => {
     delete process.env.NEXT_PRIVATE_MINIMAL_MODE
@@ -42,3 +39,40 @@ describe('react-18-streaming-ssr in minimal mode', () => {
     expect(html).toContain('static streaming')
   })
 })
+
+describe('react 18 streaming SSR with custom next configs', () => {
+  let next: NextInstance
+
+  beforeAll(async () => {
+    next = await createNext({
+      files: {
+        'pages/hello.js': `
+          export default function Page() { 
+            return <p>hello</p>
+          }
+        `,
+      },
+      nextConfig: {
+        trailingSlash: true,
+        experimental: {
+          reactRoot: true,
+          runtime: 'edge',
+        },
+      },
+      dependencies: {
+        react: '18.0.0-rc.0',
+        'react-dom': '18.0.0-rc.0',
+      },
+    })
+  })
+  afterAll(() => next.destroy())
+
+  it('should redirect paths without trailing-slash and render when slash is appended', async () => {
+    const page = '/hello'
+    const html = await renderViaHTTP(next.url, page + '/')
+    const res = await fetchViaHTTP(next.url, page, {}, { redirect: 'manual' })
+
+    expect(html).toContain('hello')
+    expect(res.status).toBe(308)
+  })
+})