rollup/test/function/custom-external-resolver-sync/_config.js

var path = require( 'path' );
var assert = require( 'assert' );

module.exports = {
	description: 'uses a custom external path resolver (synchronous)',
	options: {
		plugins: [{
			resolveId: function ( id, importer ) {
				if ( importer && id[0] !== '.' ) return path.resolve( __dirname, 'js_modules', id + '.js' );
			}
		}]
	},
	exports: function ( exports ) {
		assert.ok( exports.success );
	}
};