rollup/test/function/namespaces-are-frozen/_config.js

var assert = require( 'assert' );

module.exports = {
	description: 'namespaces should be non-extensible and its properties immutatable and non-configurable',

	exports: function ( exports ) {
		const ns = exports.ns;

		function extend ( obj ) {
			'use strict';
			obj.newProperty = true;
		}

		function reconfigure ( obj ) {
			Object.defineProperty( obj, 'a', { value: null } );
		}

		function mutate ( obj ) {
			'use strict';
			obj.a = 2;
		}

		assert.throws(function () {
			extend( ns );
		});

		assert.throws(function () {
			reconfigure( ns );
		});

		assert.throws(function () {
			mutate( ns );
		});
	}
};