Add test case for client sourcemaps (#49308)

This PR adds a test case to ensure that the server reference doesn't expose actual content of the original file in its sourcemap.

Closes NEXT-1041.

test/e2e/app-dir/actions/app-action.test.ts

@@ -1,6 +1,8 @@
 import { createNextDescribe } from 'e2e-utils'
 import { check } from 'next-test-utils'
 import { Request } from 'playwright-chromium'
+import fs from 'fs-extra'
+import { join } from 'path'
 
 const GENERIC_RSC_ERROR =
   'Error: An error occurred in the Server Components render. The specific message is omitted in production builds to avoid leaking sensitive details. A digest property is included on this error instance which may provide additional details about the nature of the error.'
@@ -170,6 +172,24 @@ createNextDescribe(
       await check(() => browser.elementByCss('h1').text(), '3')
     })
 
+    if (!isNextDev) {
+      it('should not expose action content in sourcemaps', async () => {
+        const sourcemap = (
+          await fs.readdir(
+            join(next.testDir, '.next', 'static', 'chunks', 'app', 'client')
+          )
+        ).find((f) => f.endsWith('.js.map'))
+
+        expect(sourcemap).toBeDefined()
+
+        expect(
+          await next.readFile(
+            join('.next', 'static', 'chunks', 'app', 'client', sourcemap)
+          )
+        ).not.toContain('this_is_sensitive_info')
+      })
+    }
+
     if (isNextDev) {
       describe('HMR', () => {
         it('should support updating the action', async () => {

test/e2e/app-dir/actions/app/client/actions.js

@@ -11,6 +11,7 @@ export async function dec(value) {
 }
 
 export default async function (value) {
+  console.log('this_is_sensitive_info')
   return value * 2
 }
 

test/e2e/app-dir/actions/next.config.js

@@ -1,5 +1,6 @@
 /** @type {import('next').NextConfig} */
 module.exports = {
+  productionBrowserSourceMaps: true,
   experimental: {
     serverActions: true,
   },