fix process polyfill on middleware (#34426)

Fixes the problem that global `process` variable has only the `env` field.
Also fixed the issue that the `env` field is empty when the `process` module is used as the value of the variable (which happens when the module is contained in a dependency of application).

## Bug

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

packages/next/build/webpack/loaders/next-middleware-loader.ts

@@ -12,6 +12,13 @@ export default function middlewareLoader(this: any) {
   return `
         import { adapter } from 'next/dist/server/web/adapter'
 
+        // The condition is true when the "process" module is provided
+        if (process !== global.process) {
+          // prefer local process but global.process has correct "env"
+          process.env = global.process.env;
+          global.process = process;
+        }
+
         var mod = require(${stringifiedPagePath})
         var handler = mod.middleware || mod.default;
 

packages/next/server/web/sandbox/context.ts

@@ -202,6 +202,7 @@ function createContext(options: {
     File,
     FormData,
     process: {
+      ...polyfills.process,
       env: buildEnvironmentVariablesFrom(options.env),
     },
     ReadableStream: polyfills.ReadableStream,

packages/next/server/web/sandbox/polyfills.ts

@@ -1,6 +1,7 @@
 import { Crypto as WebCrypto } from 'next/dist/compiled/@peculiar/webcrypto'
 import { CryptoKey } from 'next/dist/compiled/@peculiar/webcrypto'
 import { v4 as uuid } from 'next/dist/compiled/uuid'
+import processPolyfill from 'next/dist/compiled/process'
 import { ReadableStream } from './readable-stream'
 
 import crypto from 'crypto'
@@ -13,7 +14,7 @@ export function btoa(str: string) {
   return Buffer.from(str, 'binary').toString('base64')
 }
 
-export { CryptoKey, ReadableStream }
+export { CryptoKey, ReadableStream, processPolyfill as process }
 
 export class Crypto extends WebCrypto {
   // @ts-ignore Remove once types are updated and we deprecate node 12

packages/next/types/misc.d.ts

@@ -331,6 +331,11 @@ declare module 'next/dist/compiled/comment-json' {
   export = m
 }
 
+declare module 'next/dist/compiled/process' {
+  import m from 'process'
+  export = m
+}
+
 declare module 'pnp-webpack-plugin' {
   import webpack from 'webpack4'
 

test/integration/middleware/core/pages/global/_middleware.js

@@ -0,0 +1,12 @@
+import { NextResponse } from 'next/server'
+
+export async function middleware(request, ev) {
+  console.log(process.env.MIDDLEWARE_TEST)
+
+  return NextResponse.json({
+    process: {
+      env: process.env,
+      nextTick: typeof process.nextTick,
+    },
+  })
+}

test/integration/middleware/core/test/index.test.js

@@ -108,6 +108,30 @@ describe('Middleware base tests', () => {
       }
     })
   })
+
+  describe('global', () => {
+    beforeAll(async () => {
+      context.appPort = await findPort()
+      context.app = await launchApp(context.appDir, context.appPort, {
+        env: {
+          MIDDLEWARE_TEST: 'asdf',
+        },
+      })
+    })
+
+    it('should contains process polyfill', async () => {
+      const res = await fetchViaHTTP(context.appPort, `/global`)
+      const json = await res.json()
+      expect(json).toEqual({
+        process: {
+          env: {
+            MIDDLEWARE_TEST: 'asdf',
+          },
+          nextTick: 'function',
+        },
+      })
+    })
+  })
 })
 
 function urlTests(_log, locale = '') {