• Rollup Plugin Name: @rollup/plugin-commonjs
• Rollup Plugin Version: 28.0.2
• Rollup Version: 4.34.8
• Operating System (or Browser): macOS Sonoma 14.7.4
• Node Version: v22.14 (same for v18.20.3 used for StackBlitz reproduction)
• Link to reproduction (⚠️ read below): https://stackblitz.com/edit/rollup-repro-dlcqpdde?file=package.json

There's an extremely simple commonjs module:

module.exports.foo = 'bar'

and a simple main.js file (please not asterisk import)

import * as module from './module.cjs';

console.log('foo' in module)

Expected Behavior

For a typical node js execution it prints true:

❯ npm run exec:dev

> [email protected] exec:dev
> node src/main.js

true

Actual Behavior

For the build's execution it returns false

❯ npm run exec:build

> [email protected] exec:build
> node dist/main.js

false

Additional Information

If I change the rollup build treeshake option to true (default value), then it works as expected.

 treeshake: false

If I change the asterisk import to a default import, it works as expected.

import module from './module.cjs';