"use strict"; let value = 1; const Base = { set test(v) { value = v; } }; const obj = { test: 2, set() { return super.test = 3; }, }; Object.setPrototypeOf(obj, Base); expect(obj.set()).toBe(3); expect(value).toBe(3); expect(Base.test).toBeUndefined(); expect(obj.test).toBe(2);