var Base = { }; Object.defineProperty(Base, 'test', { value: 1, writable: false, configurable: true, }); var obj = { test: 2, set() { return super.test = 3; }, }; Object.setPrototypeOf(obj, Base); expect(obj.set()).toBe(3); expect(Base.test).toBe(1); expect(obj.test).toBe(2);