'use strict';
  
  var aFrom   = require('es5-ext/array/from')
    , toArray = require('es5-ext/array/to-array');
  
  module.exports = function (T, a) {
  	var arr = ['raz', 'dwa', 'trzy'], set = new T(arr), x = {}, y = {}, i = 0;
  
  	a(set instanceof T, true, "Set");
  	a(set.size, 3, "Size");
  	a(set.has('raz'), true, "Has: true");
  	a(set.has(x), false, "Has: false");
  	a(set.add(x), set, "Add: return");
  	a(set.has(x), true, "Add");
  	a(set.size, 4, "Add: Size");
  	a(set.delete({}), false, "Delete: false");
  
  	arr.push(x);
  	set.forEach(function () {
  		a.deep(aFrom(arguments), [arr[i], arr[i], set],
  			"ForEach: Arguments:  #" + i);
  		a(this, y, "ForEach: Context: #" + i);
  		if (i === 0) {
  			a(set.delete('raz'), true, "Delete: true");
  			a(set.has('raz'), false, "Delete");
  			a(set.size, 3, "Delete: size");
  			set.add('cztery');
  			arr.push('cztery');
  		}
  		i++;
  	}, y);
  	arr.splice(0, 1);
  
  	a.deep(toArray(set.entries()), [['dwa', 'dwa'], ['trzy', 'trzy'], [x, x],
  		['cztery', 'cztery']], "Entries");
  	a.deep(toArray(set.keys()), ['dwa', 'trzy', x, 'cztery'], "Keys");
  	a.deep(toArray(set.values()), ['dwa', 'trzy', x, 'cztery'], "Values");
  	a.deep(toArray(set), ['dwa', 'trzy', x, 'cztery'], "Iterator");
  
  	set.clear();
  	a(set.size, 0, "Clear: size");
  	a(set.has('trzy'), false, "Clear: has");
  	a.deep(toArray(set), [], "Clear: Values");
  
  	a.h1("Empty initialization");
  	set = new T();
  	set.add('foo');
  	a(set.size, 1);
  	a(set.has('foo'), true);
  };