class base { constructor() { } test() { return false; } } let standin = { test() { return true; } }; class derived extends base { constructor() { super(); } test() { assertEq(super.test(), false); Object.setPrototypeOf(derived.prototype, standin); assertEq(super["test"](), true); } } new derived().test(); if (typeof reportCompare === 'function') reportCompare(0,0,"OK");