fix(exports): support default-only module shape in ESM wrapper

[BleedingDev]

Summary

• Replace createRequire(...).require('../dist/index.js') in exports/index.mjs with an ESM import.
• Normalize the loaded module shape so wrapper exports work for:
  • named export (ReactRefreshRspackPlugin)
  • default export (default)
  • direct class export
• Add a regression test that executes a copied wrapper against a default-only fixture module.

Why

In strict Bun mode, the ESM wrapper path can surface a default-only module shape where destructuring a named export is undefined.
This causes import DefaultExport, { ReactRefreshRspackPlugin } from '@rspack/plugin-react-refresh' to break depending on runtime/module interop shape.

This change keeps Node behavior intact while making the ESM wrapper resilient across runtime interop differences.

Validation

• pnpm lint
• pnpm test
• bun --bun -e "import DefaultExport, { ReactRefreshRspackPlugin } from './exports/index.mjs'; const a = new DefaultExport(); const b = new ReactRefreshRspackPlugin(); console.log(a.options.reactRefreshLoader && b.options.reactRefreshLoader ? 'ok' : 'bad');"

All pass locally.

Maintainer Question

If you prefer a narrower compatibility target for wrapper export resolution, I can adjust the normalization logic accordingly.

[gemini-code-assist]

Summary of Changes

Hello @BleedingDev, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses an issue where the ESM wrapper for @rspack/plugin-react-refresh could fail in strict Bun mode when encountering a default-only module shape. The changes enhance the wrapper's resilience by normalizing module exports, ensuring consistent behavior across different runtime interop environments, while maintaining Node.js compatibility.

Highlights

• ESM Wrapper Import Logic: Replaced createRequire with a direct ESM import for ../dist/index.js in exports/index.mjs.
• Module Shape Normalization: Implemented logic to normalize the loaded module shape, ensuring the wrapper correctly handles named, default, and direct class exports.
• Regression Test: Added a new regression test to validate the ESM wrapper's behavior with default-only fixture modules.

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Changelog

• exports/index.mjs
  • Replaced node:module's createRequire with a direct ESM import for ../dist/index.js.
  • Modified the ReactRefreshRspackPlugin assignment to include fallback logic for pluginModule?.ReactRefreshRspackPlugin, pluginModule?.default, and pluginModule itself to support various module export shapes.
• test/exports-default-fallback.spec.mts
  • Added a new test file to verify that the ESM wrapper correctly handles modules that only provide a default export. The test dynamically creates a fixture module and a modified wrapper to simulate the scenario.

Activity

• The author validated the changes locally by running pnpm lint, pnpm test, and a custom Bun script, all of which passed.

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[gemini-code-assist]

Code Review

This pull request effectively resolves an ESM wrapper issue by transitioning from createRequire to a direct ESM import, complemented by robust fallback logic to accommodate various module export structures. This is a great improvement for compatibility with different JavaScript runtimes like Bun. The inclusion of a targeted regression test for the default-only export scenario is a strong addition that validates the fix. I have one suggestion regarding the new test file to enhance its readability.

[chenjiahan]

LGTM, thank you!