rollup.config.mjs

import { babel } from '@rollup/plugin-babel';
import { Addon } from '@embroider/addon-dev/rollup';

const addon = new Addon({
  srcDir: 'src',
  destDir: 'dist',
});

export default {
  // This provides defaults that work well alongside `publicEntrypoints` below.
  // You can augment this if you need to.
  output: addon.output(),

  plugins: [
    // These are the modules that users should be able to import from your
    // addon. Anything not listed here may get optimized away.
    addon.publicEntrypoints([
      'components/**/*.js',
      'modifiers/**/*.js',
      'test-support/index.js',
    ]),

    // These are the modules that should get reexported into the traditional
    // "app" tree. Things in here should also be in publicEntrypoints above, but
    // not everything in publicEntrypoints necessarily needs to go here.
    addon.appReexports(['components/**/*.js', 'modifiers/**/*.js']),

    // This babel config should *not* apply presets or compile away ES modules.
    // It exists only to provide development niceties for you, like automatic
    // template colocation.
    babel({
      plugins: [
        '@embroider/addon-dev/template-colocation-plugin',

        // https://github.com/embroider-build/embroider/issues/1014#issuecomment-1014926434
        ['@babel/plugin-proposal-decorators', { legacy: true }],
        '@babel/plugin-proposal-class-properties',
      ],
      babelHelpers: 'bundled',
    }),

    // Follow the V2 Addon rules about dependencies. Your code can import from
    // `dependencies` and `peerDependencies` as well as standard Ember-provided
    // package names.
    addon.dependencies(),

    // Ensure that standalone .hbs files are properly integrated as Javascript.
    addon.hbs(),

    // addons are allowed to contain imports of .css files, which we want rollup
    // to leave alone and keep in the published output.
    addon.keepAssets(['**/*.css']),

    // Remove leftover build artifacts when starting a new build.
    addon.clean(),
  ],
};