count.js 296 Bytes
"use strict";

module.exports = function (t, a) {
	a(t({}), 0, "Empty");
	a(t({ raz: 1, dwa: null, trzy: undefined, cztery: 0 }), 4,
		"Some properties");
	a(t(Object.defineProperties({}, {
		raz: { value: "raz" },
		dwa: { value: "dwa", enumerable: true }
	})), 1, "Some properties hidden");
};