Extend IncomingMessage type to include cookies from middleware

packages/next/types/index.d.ts

@@ -128,7 +128,9 @@ export type GetStaticPaths<P extends ParsedUrlQuery = ParsedUrlQuery> = (
 export type GetServerSidePropsContext<
   Q extends ParsedUrlQuery = ParsedUrlQuery
 > = {
-  req: IncomingMessage
+  req: IncomingMessage & {
+    cookies?: { [key: string]: any }
+  }
   res: ServerResponse
   params?: Q
   query: ParsedUrlQuery

test/integration/typescript/pages/ssr/cookies.tsx

@@ -0,0 +1,18 @@
+import { GetServerSideProps } from 'next'
+
+type Props = {
+  data: string
+  cookies: any
+}
+
+export const getServerSideProps: GetServerSideProps<Props> = async ({
+  req,
+}) => {
+  return {
+    props: { data: 'hello world', cookies: req.cookies },
+  }
+}
+
+export default function Page({ cookies }: Props) {
+  return <pre id="cookies">{JSON.stringify(cookies)}</pre>
+}

test/integration/typescript/test/index.test.js

@@ -46,6 +46,11 @@ describe('TypeScript Features', () => {
       expect($('body').text()).toMatch(/1000000000000/)
     })
 
+    it('should render the cookies page', async () => {
+      const $ = await get$('/ssr/cookies')
+      expect($('#cookies').text()).toBe('{}')
+    })
+
     it('should resolve files in correct order', async () => {
       const $ = await get$('/hello')
       expect($('#imported-value').text()).toBe('OK')