default import from a commonjs package with { __esModule: true } fails in runtime

[vskh]

• Rollup Plugin Name: commonjs
• Rollup Plugin Version: 25.0.7
• Rollup Version: 4.1.4
• Operating System (or Browser): Linux 5.15.123.1-microsoft-standard-WSL2 x86_64
• Node Version: v18.16.0
• Link to reproduction (⚠️ read below): https://stackblitz.com/edit/rollup-repro-wx5pcy

Expected Behavior

Following import: import userEvent from "@testing-library/user-event";

to be transpiled into: var userEvent = require('@testing-library/user-event').default;

because '@testing-library/user-event' defines exports["default"] and Object.defineProperty(exports, '__esModule', { value: true });.

From 'plugin-commonjs' docs:

defaultIsModuleExports Default: "auto"

"auto": The value of the default export is exports.default if the CommonJS file has an exports.__esModule === true property; otherwise it's module.exports. This makes it possible to import the default export of ES modules compiled to CommonJS as if they were not compiled.

Actual Behavior

Following import: import userEvent from "@testing-library/user-event";

to be transpiled into: var userEvent = require('@testing-library/user-event');

Additional Information

Existing behavior causes compiled code to fail at runtime because it tries to access properties of default export, whereas require result is an object with only 'default' key.

[simonsmith]

@vskh I've hit this same issue. Did you find a way to work round it?

[simonsmith]

Just to follow up, I found that the interop option solved this:

    {
      dir: 'dist/cjs',
      format: 'cjs',
      sourcemap: true,
+     interop: 'auto',
    },

https://rollupjs.org/configuration-options/#output-interop