fix: cjs exports has Object.prototype instead of null (#2769)

* fix: cjs exports has Object.prototype instead of null

* chore: cleanup

packages/vite-node/src/client.ts

@@ -310,8 +310,15 @@ export class ViteNodeRunner {
       enumerable: false,
       configurable: false,
     })
-    // this prosxy is triggered only on exports.{name} and module.exports access
+    // this proxy is triggered only on exports.{name} and module.exports access
+    // inside the module itself. imported module is always "exports"
     const cjsExports = new Proxy(exports, {
+      get: (target, p, receiver) => {
+        if (Reflect.has(target, p))
+          return Reflect.get(target, p, receiver)
+        return Reflect.get(Object.prototype, p, receiver)
+      },
+      getPrototypeOf: () => Object.prototype,
       set: (_, p, value) => {
         // treat "module.exports =" the same as "exports.default =" to not have nested "default.default",
         // so "exports.default" becomes the actual module

test/cjs/src/prototype.cjs

@@ -0,0 +1,7 @@
+exports.test = () => {
+  // eslint-disable-next-line no-prototype-builtins
+  return exports.hasOwnProperty('test')
+}
+exports.getPrototype = () => {
+  return Object.getPrototypeOf(exports)
+}

test/cjs/src/prototype.d.cts

@@ -0,0 +1,2 @@
+export const test: () => boolean
+export const getPrototype: () => any

test/cjs/test/prototype.test.ts

@@ -0,0 +1,8 @@
+import { expect, it } from 'vitest'
+import * as cjsExports from '../src/prototype.cjs'
+
+it('has object prototype', () => {
+  expect(cjsExports.getPrototype()).toBe(Object.prototype)
+  expect(() => cjsExports.test()).not.toThrow()
+  expect(cjsExports.test()).toBe(true)
+})

test/esm/src/prototype.d.mts

@@ -0,0 +1 @@
+declare export const test: number

test/esm/src/prototype.mjs

@@ -0,0 +1 @@
+export const test = 1

test/esm/test/prototype.spec.ts

@@ -0,0 +1,8 @@
+import { expect, it } from 'vitest'
+import * as exports from '../src/prototype.mjs'
+
+it('prototype is null', () => {
+  expect(Object.getPrototypeOf(exports)).toBe(null)
+  expect({}.hasOwnProperty).toBeTypeOf('function')
+  expect(exports.hasOwnProperty).toBeTypeOf('undefined')
+})

test/esm/vite.config.ts

@@ -3,7 +3,7 @@ import { defineConfig } from 'vitest/config'
 export default defineConfig({
   test: {
     deps: {
-      external: [/tslib/, /css-what/],
+      external: [/tslib/, /css-what/, /prototype\.mjs/],
       registerNodeLoader: true,
     },
   },