fix(rsc): fix cjs default import on module runner

packages/plugin-rsc/src/plugins/cjs.ts

@@ -56,7 +56,10 @@ export function cjsModuleRunnerPlugin(): Plugin[] {
           // TODO: can we use cjs-module-lexer to properly define named exports?
           // for re-exports, we need to eagerly transform dependencies though.
           // https://github.com/nodejs/node/blob/f3adc11e37b8bfaaa026ea85c1cf22e3a0e29ae9/lib/internal/modules/esm/translators.js#L382-L409
-          output.append(`__vite_ssr_exportAll__(module.exports)`)
+          output.append(`
+;__vite_ssr_exportAll__(module.exports);
+export default module.exports;
+`)
           return {
             code: output.toString(),
             map: output.generateMap({ hires: 'boundary' }),

packages/plugin-rsc/src/transforms/cjs.test.ts

@@ -1,7 +1,8 @@
-import { parseAstAsync } from 'vite'
+import { createServer, createServerModuleRunner, parseAstAsync } from 'vite'
 import { describe, expect, it } from 'vitest'
 import { debugSourceMap } from './test-utils'
 import { transformCjsToEsm } from './cjs'
+import path from 'node:path'
 
 describe(transformCjsToEsm, () => {
   async function testTransform(input: string) {
@@ -83,4 +84,51 @@ if (true) {
       "
     `)
   })
+
+  it('e2e', async () => {
+    const server = await createServer({
+      configFile: false,
+      logLevel: 'error',
+      root: path.join(import.meta.dirname, 'fixtures/cjs'),
+      plugins: [
+        {
+          name: 'cjs-module-runner-transform',
+          async transform(code, id) {
+            if (id.endsWith('.cjs')) {
+              const ast = await parseAstAsync(code)
+              const { output } = transformCjsToEsm(code, ast)
+              output.append(`
+;__vite_ssr_exportAll__(module.exports);
+export default module.exports;
+`)
+              return {
+                code: output.toString(),
+                map: output.generateMap({ hires: 'boundary' }),
+              }
+            }
+          },
+        },
+      ],
+    })
+    const runner = createServerModuleRunner(server.environments.ssr, {
+      hmr: false,
+    })
+    const mod = await runner.import('/entry.mjs')
+    expect(mod).toMatchInlineSnapshot(`
+      {
+        "depDefault": {
+          "a": "a",
+          "b": "b",
+        },
+        "depNamespace": {
+          "a": "a",
+          "b": "b",
+          "default": {
+            "a": "a",
+            "b": "b",
+          },
+        },
+      }
+    `)
+  })
 })

packages/plugin-rsc/src/transforms/fixtures/cjs/dep1.cjs

@@ -0,0 +1,2 @@
+exports.a = 'a'
+exports.b = 'b'

packages/plugin-rsc/src/transforms/fixtures/cjs/dep2.cjs

@@ -0,0 +1,2 @@
+exports.a = 'a'
+exports.b = 'b'

packages/plugin-rsc/src/transforms/fixtures/cjs/entry.mjs

@@ -0,0 +1,3 @@
+import depDefault from './dep1.cjs'
+import * as depNamespace from './dep2.cjs'
+export { depDefault, depNamespace }