feat!: improve interchangeability with cjs

packages/vite-node/src/client.ts

@@ -235,12 +235,27 @@ export class ViteNodeRunner {
     // disambiguate the `<UNIT>:/` on windows: see nodejs/node#31710
     const url = pathToFileURL(fsPath).href
     const meta = { url }
-    const exports: any = Object.create(null)
-    Object.defineProperty(exports, Symbol.toStringTag, {
+    const exportsBase: any = Object.create(null)
+    Object.defineProperty(exportsBase, Symbol.toStringTag, {
       value: 'Module',
       enumerable: false,
       configurable: false,
     })
+    const exports = new Proxy(exportsBase, {
+      set(target, p, value, receiver) {
+        const result = Reflect.set(target, p, value, receiver)
+        if (p !== 'default') {
+          if (!Reflect.has(target, 'default'))
+            target.default = {}
+
+          // Node also allows access of named exports via exports.default
+          // https://nodejs.org/api/esm.html#commonjs-namespaces
+          if (target.default && typeof target.default === 'object')
+            target.default[p] = value
+        }
+        return result
+      },
+    })
 
     Object.assign(mod, { code: transformed, exports })
 

test/core/test/module.test.ts

@@ -1,7 +1,7 @@
 import { expect, it } from 'vitest'
 // eslint-disable-next-line @typescript-eslint/ban-ts-comment
 // @ts-expect-error
-import { a, b } from '../src/module-cjs'
+import cjs, { a, b } from '../src/module-cjs'
 import c, { d } from '../src/module-esm'
 import * as timeout from '../src/timeout'
 
@@ -10,6 +10,8 @@ it('doesn\'t when extending module', () => {
 })
 
 it('should work when using cjs module', () => {
+  expect(cjs.a).toBe(1)
+  expect(cjs.b).toBe(2)
   expect(a).toBe(1)
   expect(b).toBe(2)
 })