1const util = require('util'); 2const assert = require('assert'); 3 4class deprecatedClass { 5} 6 7const deprecated = util.deprecate(deprecatedClass, 'deprecatedClass is deprecated.'); 8 9class subclass extends deprecated { 10 constructor() { 11 super(); 12 } 13} 14 15const instance = new subclass(); 16 17assert(instance instanceof subclass); 18assert(instance instanceof deprecated); 19assert(instance instanceof deprecatedClass); 20