Ensure isReady is set correctly for auto static dynamic route (#20729)

Follow-up to https://github.com/vercel/next.js/pull/20628 this ensures `isReady` is not initially true when the query isn't present but the page is an automatically statically optimized dynamic route

packages/next/next-server/lib/router/router.ts

@@ -535,8 +535,10 @@ export default class Router implements BaseRouter {
     this.query = query
     // if auto prerendered and dynamic route wait to update asPath
     // until after mount to prevent hydration mismatch
-    this.asPath =
-      isDynamicRoute(pathname) && self.__NEXT_DATA__.autoExport ? pathname : as
+    const autoExportDynamic =
+      isDynamicRoute(pathname) && self.__NEXT_DATA__.autoExport
+
+    this.asPath = autoExportDynamic ? pathname : as
     this.basePath = basePath
     this.sub = subscription
     this.clc = null
@@ -550,7 +552,7 @@ export default class Router implements BaseRouter {
     this.isReady = !!(
       self.__NEXT_DATA__.gssp ||
       self.__NEXT_DATA__.gip ||
-      !self.location.search
+      (!autoExportDynamic && !self.location.search)
     )
 
     if (process.env.__NEXT_I18N_SUPPORT) {

test/integration/build-output/test/index.test.js

@@ -101,7 +101,7 @@ describe('Build Output', () => {
       expect(parseFloat(err404Size) - 3.7).toBeLessThanOrEqual(0)
       expect(err404Size.endsWith('kB')).toBe(true)
 
-      expect(parseFloat(err404FirstLoad)).toBeCloseTo(65.4, 1)
+      expect(parseFloat(err404FirstLoad)).toBeCloseTo(65.5, 1)
       expect(err404FirstLoad.endsWith('kB')).toBe(true)
 
       expect(parseFloat(sharedByAll)).toBeCloseTo(62, 1)

test/integration/router-is-ready/pages/auto-export/index.js

+import { useRouter } from 'next/router'
+
+export default function Page(props) {
+  const router = useRouter()
+
+  if (typeof window !== 'undefined') {
+    if (!window.isReadyValues) {
+      window.isReadyValues = []
+    }
+    window.isReadyValues.push(router.isReady)
+  }
+
+  return (
+    <>
+      <p id="auto-export">auto-export page</p>
+    </>
+  )
+}

test/integration/router-is-ready/test/index.test.js

@@ -49,6 +49,16 @@ function runTests(isDev) {
     expect(await browser.eval('window.isReadyValues')).toEqual([false, true])
   })
 
+  it('isReady should be true after query update for dynamic auto-export page without query', async () => {
+    const browser = await webdriver(appPort, '/auto-export/first')
+    expect(await browser.eval('window.isReadyValues')).toEqual([false, true])
+  })
+
+  it('isReady should be true after query update for dynamic auto-export page with query', async () => {
+    const browser = await webdriver(appPort, '/auto-export/first?hello=true')
+    expect(await browser.eval('window.isReadyValues')).toEqual([false, true])
+  })
+
   it('isReady should be true after query update for getStaticProps page with query', async () => {
     const browser = await webdriver(appPort, '/gsp?hello=world')
     expect(await browser.eval('window.isReadyValues')).toEqual([false, true])