objects.js
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objects.js
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	import { test, testDeep, testThrows, summary } from './helpers.js';

	console.log('Object Tests\n');

	let obj = { a: 1, b: 2, c: 3 };
	test('object property access', obj.a, 1);
	test('object bracket access', obj['b'], 2);
	test('object property count', Object.keys(obj).length, 3);

	obj.d = 4;
	test('add property', obj.d, 4);

	obj.a = 10;
	test('modify property', obj.a, 10);

	delete obj.d;
	test('delete property', obj.d, undefined);

	test('in operator true', 'a' in obj, true);
	test('in operator false', 'z' in obj, false);

	testDeep('Object.keys', Object.keys({ x: 1, y: 2 }), ['x', 'y']);
	testDeep('Object.values', Object.values({ x: 1, y: 2 }), [1, 2]);
	testDeep('Object.entries', Object.entries({ x: 1 }), [['x', 1]]);

	let merged = Object.assign({}, { a: 1 }, { b: 2 });
	test('Object.assign a', merged.a, 1);
	test('Object.assign b', merged.b, 2);

	let nested = { a: { b: { c: 1 } } };
	test('nested access', nested.a.b.c, 1);

	let computed = { ['key' + 1]: 'value' };
	test('computed property', computed.key1, 'value');

	let short = 'hello';
	let shorthand = { short };
	test('shorthand property', shorthand.short, 'hello');

	let methodObj = {
	value: 42,
	getValue() {
	return this.value;
	}
	};
	test('method shorthand', methodObj.getValue(), 42);

	let source = { a: 1, b: 2 };
	let spread = { ...source, c: 3 };
	test('spread a', spread.a, 1);
	test('spread c', spread.c, 3);

	let { a, b } = { a: 1, b: 2, c: 3 };
	test('destructuring a', a, 1);
	test('destructuring b', b, 2);

	let { x: renamed } = { x: 5 };
	test('destructuring rename', renamed, 5);

	let { y = 10 } = {};
	test('destructuring default', y, 10);

	test('hasOwnProperty true', { a: 1 }.hasOwnProperty('a'), true);
	test('hasOwnProperty false', { a: 1 }.hasOwnProperty('b'), false);

	let frozen = Object.freeze({ a: 1 });
	test('Object.isFrozen', Object.isFrozen(frozen), true);

	let sealed = Object.seal({ a: 1 });
	test('Object.isSealed', Object.isSealed(sealed), true);

	let proto = { inherited: true };
	let child = Object.create(proto);
	test('Object.create inherits', child.inherited, true);

	test('Object.getPrototypeOf', Object.getPrototypeOf([]) === Array.prototype, true);

	testDeep(
	'Object.fromEntries',
	Object.fromEntries([
	['a', 1],
	['b', 2]
	]),
	{ a: 1, b: 2 }
	);

	let descriptorSource = {};
	const descriptorSymbol = Symbol('descriptor');
	Object.defineProperty(descriptorSource, 'hidden', {
	value: 42,
	enumerable: false,
	writable: false,
	configurable: false
	});
	Object.defineProperty(descriptorSource, 'computed', {
	get() {
	return 7;
	},
	enumerable: true,
	configurable: true
	});
	descriptorSource.visible = 'yes';
	descriptorSource[descriptorSymbol] = 'symbol value';

	const descriptors = Object.getOwnPropertyDescriptors(descriptorSource);
	test('Object.getOwnPropertyDescriptors exists', typeof Object.getOwnPropertyDescriptors, 'function');
	test('descriptors data value', descriptors.visible.value, 'yes');
	test('descriptors hidden value', descriptors.hidden.value, 42);
	test('descriptors hidden enumerable', descriptors.hidden.enumerable, false);
	test('descriptors hidden writable', descriptors.hidden.writable, false);
	test('descriptors hidden configurable', descriptors.hidden.configurable, false);
	test('descriptors accessor getter', typeof descriptors.computed.get, 'function');
	test('descriptors accessor enumerable', descriptors.computed.enumerable, true);
	test('descriptors symbol value', descriptors[descriptorSymbol].value, 'symbol value');

	const arrayDescriptors = Object.getOwnPropertyDescriptors(['item']);
	test('array descriptor index value', arrayDescriptors[0].value, 'item');
	test('array descriptor length value', arrayDescriptors.length.value, 1);
	const proxyUndefinedDescriptor = new Proxy({ a: 1 }, {
	getOwnPropertyDescriptor() {}
	});
	test('Object.getOwnPropertyDescriptors skips undefined proxy descriptors', Object.getOwnPropertyDescriptors(proxyUndefinedDescriptor).hasOwnProperty('a'), false);
	testThrows('Object.getOwnPropertyDescriptors throws without argument', () => Object.getOwnPropertyDescriptors());
	testThrows('Object.getOwnPropertyDescriptors throws on null', () => Object.getOwnPropertyDescriptors(null));
	test('Object.getOwnPropertyDescriptors boxes number primitive', typeof Object.getOwnPropertyDescriptors(1), 'object');

	summary();

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