"use strict";
class Base {
}

class Obj extends Base {
  set() {
    return super.test = 3;
  }
}

const obj = new Obj();
expect(obj.set()).toBe(3);
expect(Base.prototype.test).toBeUndefined();
expect(Obj.prototype.test).toBeUndefined();
expect(obj.test).toBe(3);