Add handling for exportTrailingSlash for iSSG pages (#9258)

* Add handling for exportTrailingSlash for iSSG pages

* Update index.test.js

packages/next/export/index.ts

@@ -3,7 +3,7 @@ import { copyFile as copyFileOrig, existsSync, readFileSync } from 'fs'
 import Worker from 'jest-worker'
 import mkdirpModule from 'mkdirp'
 import { cpus } from 'os'
-import { dirname, join, resolve } from 'path'
+import { dirname, join, resolve, sep } from 'path'
 import { promisify } from 'util'
 
 import { AmpPageStatus, formatAmpMessages } from '../build/output/index'
@@ -321,7 +321,12 @@ export default async function(
       Object.keys(prerenderManifest.routes).map(async route => {
         route = route === '/' ? '/index' : route
         const orig = join(distPagesDir, route)
-        const htmlDest = join(outDir, `${route}.html`)
+        const htmlDest = join(
+          outDir,
+          `${route}${
+            subFolders && route !== '/index' ? `${sep}index` : ''
+          }.html`
+        )
         const jsonDest = join(sprDataDir, `${route}.json`)
 
         await mkdirp(dirname(htmlDest))

test/integration/prerender/pages/blog/index.js

+import React from 'react'
+import Link from 'next/link'
+
+// eslint-disable-next-line camelcase
+export async function unstable_getStaticProps () {
+  return {
+    props: {
+      slugs: ['post-1', 'post-2'],
+      time: (await import('perf_hooks')).performance.now()
+    },
+    revalidate: 10
+  }
+}
+
+export default ({ slugs, time }) => {
+  return (
+    <>
+      <p>Posts: {JSON.stringify(slugs)}</p>
+      <span>time: {time}</span>
+      <Link href='/'>
+        <a id='home'>to home</a>
+      </Link>
+    </>
+  )
+}

test/integration/prerender/test/index.test.js

@@ -12,6 +12,7 @@ import {
   waitFor,
   nextBuild,
   nextStart,
+  stopApp,
   nextExport,
   startStaticServer,
   initNextServerScript
@@ -85,6 +86,11 @@ const expectedManifestRoutes = () => ({
     initialRevalidateSeconds: 0,
     srcRoute: null
   },
+  '/blog': {
+    dataRoute: `/_next/data/${buildId}/blog.json`,
+    initialRevalidateSeconds: 10,
+    srcRoute: null
+  },
   '/default-revalidate': {
     dataRoute: `/_next/data/${buildId}/default-revalidate.json`,
     initialRevalidateSeconds: 1,
@@ -449,9 +455,7 @@ describe('SPR Prerender', () => {
 
   describe('production mode', () => {
     beforeAll(async () => {
-      try {
-        await fs.unlink(nextConfig)
-      } catch (_) {}
+      await fs.remove(nextConfig)
       await nextBuild(appDir)
       stderr = ''
       appPort = await findPort()
@@ -471,15 +475,22 @@ describe('SPR Prerender', () => {
   describe('export mode', () => {
     beforeAll(async () => {
       exportDir = join(appDir, 'out')
+      await fs.writeFile(
+        nextConfig,
+        `module.exports = { exportTrailingSlash: true }`
+      )
       await nextBuild(appDir)
       await nextExport(appDir, { outdir: exportDir })
       app = await startStaticServer(exportDir)
       appPort = app.address().port
       buildId = await fs.readFile(join(appDir, '.next/BUILD_ID'), 'utf8')
     })
-    afterAll(() => killApp(app))
+    afterAll(async () => {
+      await stopApp(app)
+      await fs.remove(nextConfig)
+    })
 
-    it('should copy prerender files correctly', async () => {
+    it('should copy prerender files and honor exportTrailingSlash', async () => {
       const routes = [
         '/another',
         '/something',
@@ -488,7 +499,7 @@ describe('SPR Prerender', () => {
       ]
 
       for (const route of routes) {
-        await fs.access(join(exportDir, `${route}.html`))
+        await fs.access(join(exportDir, `${route}/index.html`))
         await fs.access(join(exportDir, '_next/data', buildId, `${route}.json`))
       }
     })