core-js/tests/unit-global/es.object.lookup-setter.js

import { DESCRIPTORS, STRICT } from '../helpers/constants.js';

if (DESCRIPTORS) {
  QUnit.test('Object#__lookupSetter__', assert => {
    const { __lookupSetter__ } = Object.prototype;
    const { create } = Object;
    assert.isFunction(__lookupSetter__);
    assert.arity(__lookupSetter__, 1);
    assert.name(__lookupSetter__, '__lookupSetter__');
    assert.looksNative(__lookupSetter__);
    assert.nonEnumerable(Object.prototype, '__lookupSetter__');
    assert.same({}.__lookupSetter__('key'), undefined, 'empty object');
    assert.same({ key: 42 }.__lookupSetter__('key'), undefined, 'data descriptor');
    const object = {};
    function setter() { /* empty */ }
    object.__defineSetter__('key', setter);
    assert.same(object.__lookupSetter__('key'), setter, 'own setter');
    assert.same(create(object).__lookupSetter__('key'), setter, 'proto setter');
    assert.same(create(object).__lookupSetter__('foo'), undefined, 'empty proto');
    if (STRICT) {
      assert.throws(() => __lookupSetter__.call(null, 1, () => { /* empty */ }), TypeError, 'Throws on null as `this`');
      assert.throws(() => __lookupSetter__.call(undefined, 1, () => { /* empty */ }), TypeError, 'Throws on undefined as `this`');
    }
  });
}