Ensure next-server prepare only execute once

test/e2e/instrumentation-hook/register-once/instrumentation.js

@@ -1,5 +1,11 @@
+let count = 0
+
 export function register() {
   if (process.env.NEXT_RUNTIME === 'nodejs') {
+    if (count > 0) {
+      throw new Error('duplicated-register')
+    }
     console.log('register-log')
+    count++
   }
 }

test/e2e/instrumentation-hook/register-once/register-once.test.ts

@@ -1,17 +1,18 @@
 import { nextTestSetup } from 'e2e-utils'
 
 describe('instrumentation-hook - register-once', () => {
-  const { next, skipped } = nextTestSetup({
+  const { next } = nextTestSetup({
     files: __dirname,
-    skipDeployment: true,
   })
 
-  if (skipped) {
-    return
-  }
-
   it('should only register once', async () => {
     await next.fetch('/foo')
     expect(next.cliOutput).toIncludeRepeated('register-log', 1)
   })
+
+  it('should not error when concurrent requests are made', async () => {
+    await Promise.all([next.fetch('/foo'), next.fetch('/foo')])
+    expect(next.cliOutput).toIncludeRepeated('register-log', 1)
+    expect(next.cliOutput).not.toInclude('duplicated-register')
+  })
 })