diff --git a/playground/js-sourcemap/__tests__/js-sourcemap.spec.ts b/playground/js-sourcemap/__tests__/js-sourcemap.spec.ts
index 14daa7654c08a5..b4e63e66290a74 100644
--- a/playground/js-sourcemap/__tests__/js-sourcemap.spec.ts
+++ b/playground/js-sourcemap/__tests__/js-sourcemap.spec.ts
@@ -1,6 +1,7 @@
 import { URL } from 'node:url'
 import { describe, expect, test } from 'vitest'
 import { mapFileCommentRegex } from 'convert-source-map'
+import { commentSourceMap } from '../foo-with-sourcemap-plugin'
 import {
   extractSourcemap,
   findAssetFile,
@@ -30,12 +31,13 @@ if (!isBuild) {
     `)
   })
 
-  test('js with existing inline sourcemap', async () => {
+  test('js with inline sourcemap injected by a plugin', async () => {
     const res = await page.request.get(
       new URL('./foo-with-sourcemap.js', page.url()).href,
     )
     const js = await res.text()
 
+    expect(js).toContain(commentSourceMap)
     const sourcemapComments = js.match(mapFileCommentRegex).length
     expect(sourcemapComments).toBe(1)
 
@@ -46,9 +48,6 @@ if (!isBuild) {
         "sources": [
           "",
         ],
-        "sourcesContent": [
-          null,
-        ],
         "version": 3,
       }
     `)
diff --git a/playground/js-sourcemap/foo-with-sourcemap-plugin.ts b/playground/js-sourcemap/foo-with-sourcemap-plugin.ts
new file mode 100644
index 00000000000000..a181c39eaf6036
--- /dev/null
+++ b/playground/js-sourcemap/foo-with-sourcemap-plugin.ts
@@ -0,0 +1,17 @@
+import type { Plugin } from 'vite'
+
+export const commentSourceMap = [
+  '// default boundary sourcemap with magic-string',
+  '//# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbIiJdLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiQUFBQSxNQUFNLENBQUMsS0FBSyxDQUFDLEdBQUcsQ0FBQyxDQUFDLENBQUMsQ0FBQyxHQUFHIn0=',
+].join('\n')
+
+export default function transformFooWithInlineSourceMap(): Plugin {
+  return {
+    name: 'transform-foo-with-inline-sourcemap',
+    transform(code, id) {
+      if (id.includes('foo-with-sourcemap.js')) {
+        return `${code}${commentSourceMap}`
+      }
+    },
+  }
+}
diff --git a/playground/js-sourcemap/foo-with-sourcemap.js b/playground/js-sourcemap/foo-with-sourcemap.js
index 571667802fbf05..cb356468240d50 100644
--- a/playground/js-sourcemap/foo-with-sourcemap.js
+++ b/playground/js-sourcemap/foo-with-sourcemap.js
@@ -1,5 +1 @@
 export const foo = 'foo'
-
-// default boundary sourcemap with magic-string
-
-//# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbIiJdLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiQUFBQSxNQUFNLENBQUMsS0FBSyxDQUFDLEdBQUcsQ0FBQyxDQUFDLENBQUMsQ0FBQyxHQUFHIn0=
diff --git a/playground/js-sourcemap/vite.config.js b/playground/js-sourcemap/vite.config.js
index b56e74e40f3633..efebbc5ca00dee 100644
--- a/playground/js-sourcemap/vite.config.js
+++ b/playground/js-sourcemap/vite.config.js
@@ -1,6 +1,8 @@
 import { defineConfig } from 'vite'
+import transformFooWithInlineSourceMap from './foo-with-sourcemap-plugin'
 
 export default defineConfig({
+  plugins: [transformFooWithInlineSourceMap()],
   build: {
     sourcemap: true,
     rollupOptions: {