rollup/test/function/external-ids-not-resolved/_config.js

module.exports = {
	description: 'does not attempt to resolve external IDs',
	options: {
		external: [ 'external' ],
		plugins: [
			{
				resolveId: function ( importee ) {
					if ( importee === 'external' ) {
						throw new Error( 'Attempted to resolve external module ID' );
					}
				}
			}
		]
	}
};