Prevent node inspect from causing webpack check to fail (#25876)

packages/next/next-server/server/config-utils.ts

@@ -23,13 +23,21 @@ function reasonMessage(reason: CheckReasons) {
 export async function loadWebpackHook(phase: string, dir: string) {
   let useWebpack5 = true
   let usesRemovedFlag = false
-  const worker: any = new Worker(
+  const worker = new Worker(
     path.resolve(__dirname, './config-utils-worker.js'),
     {
       enableWorkerThreads: false,
       numWorkers: 1,
+      forkOptions: {
+        env: {
+          ...process.env,
+          NODE_OPTIONS: '',
+        },
+      },
     }
-  )
+  ) as Worker & {
+    shouldLoadWithWebpack5: typeof import('./config-utils-worker').shouldLoadWithWebpack5
+  }
   try {
     const result: CheckResult = await worker.shouldLoadWithWebpack5(phase, dir)
     if (result.reason === 'future-flag') {

test/integration/config/test/index.test.js

@@ -19,8 +19,20 @@ jest.setTimeout(1000 * 60 * 5)
 
 describe('Configuration', () => {
   beforeAll(async () => {
+    context.output = ''
+
+    const handleOutput = (msg) => {
+      context.output += msg
+    }
+
     context.appPort = await findPort()
-    context.server = await launchApp(join(__dirname, '../'), context.appPort)
+    context.server = await launchApp(join(__dirname, '../'), context.appPort, {
+      env: {
+        NODE_OPTIONS: '--inspect',
+      },
+      onStdout: handleOutput,
+      onStderr: handleOutput,
+    })
 
     // pre-build all pages at the start
     await Promise.all([
@@ -40,6 +52,12 @@ describe('Configuration', () => {
     return cheerio.load(html)
   }
 
+  it('should log webpack version correctly', async () => {
+    expect(context.output).toContain(
+      `Using webpack 4. Reason: webpack5 flag is set to false in next.config.js`
+    )
+  })
+
   it('should disable X-Powered-By header support', async () => {
     const url = `http://localhost:${context.appPort}/`
     const header = (await fetch(url)).headers.get('X-Powered-By')