rollup/test/function/double-default-export/_config.js

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

module.exports = {
	description: 'throws on double default exports',
	error: {
		code: 'PARSE_ERROR',
		message: `Duplicate export 'default'`,
		pos: 25,
		loc: {
			file: path.resolve( __dirname, 'foo.js' ),
			line: 2,
			column: 7
		},
		frame: `
			1: export default 1;
			2: export default 2;
			          ^
		`
	}
};