polyfill-service/polyfills/Array/prototype/includes/tests.js

A polyfill combinator

/* eslint-env mocha, browser */
/* global proclaim */

var supportsDescriptors = Object.defineProperty && (function () {
	try {
		var obj = {};
		Object.defineProperty(obj, 'x', { enumerable: false, value: obj });
		for (var _ in obj) { return false; } // jscs:ignore disallowUnusedVariables
		return obj.x === obj;
	} catch (e) { /* this is ES3 */
		return false;
	}
}());

var ifSupportsDescriptorsIt = supportsDescriptors ? it : xit;

it('has correct instance', function () {
	proclaim.isInstanceOf(Array.prototype.includes, Function);
});

it('has correct name', function () {
	function nameOf(fn) {
		return Function.prototype.toString.call(fn).match(/function\s*([^\s]*)\s*\(/)[1];
	}
	proclaim.equal(nameOf(Array.prototype.includes), 'includes');
});

it('has correct argument length', function () {
	proclaim.equal(Array.prototype.includes.length, 1);
});

ifSupportsDescriptorsIt('is not enumerable', function () {
	proclaim.isFalse(Object.prototype.propertyIsEnumerable.call(Array.prototype, 'includes'));
});

it('handles arrays', function () {
	proclaim.equal([10, 11, 12, 13].includes(12), true);
	proclaim.equal([10, 11, 12, 13].includes(14), false);
	proclaim.equal([10, 11, 12, 13].includes(13, 4), false);
	proclaim.equal([10, 11, 12, 13].includes(13, -1), true);
});

it('handles arrays of strings', function () {
	proclaim.equal(['a', 'b', 'c'].includes('foo'), false);
	proclaim.equal(['1', '2', '3'].includes('foo'), false);
	proclaim.equal(['a', 'b', 'c'].includes(1), false);
	proclaim.equal(['1', '2', '3'].includes(3), false);
	proclaim.equal(['1', '2', '3'].includes('3'), true);
});

it('handles arrays using SameValueZero equality algorithm', function () {
	proclaim.equal([-0, 11, 12, 13].includes(+0), true);
	proclaim.equal([+0, 11, 12, 13].includes(-0), true);
	proclaim.equal([NaN, 11, 12, 13].includes(NaN), true);
});

it('handles array-like objects', function () {
	var
	// 3: 0 is ignored because length omits it
	object = { 0: NaN, 1: 11, 2: 12, 3: 13, length: 3 };

	proclaim.equal(Array.prototype.includes.call(object, 12), true);
	proclaim.equal(Array.prototype.includes.call(object, 13), false);
	proclaim.equal(Array.prototype.includes.call(object, 13, 3), false);
	proclaim.equal(Array.prototype.includes.call(object, 12, -1), true);
	proclaim.equal(Array.prototype.includes.call(object, NaN), true);
});

it('handles array-like objects with out-of-range lengths', function () {
	var
	object = { 0: 10, 1: 11, 2: 12, 3: 13, length: -Infinity };

	proclaim.equal(Array.prototype.includes.call(object, 10), false);
	proclaim.equal(Array.prototype.includes.call(object, 10), false);
});