public function setUp()
{
parent::setUp();
$this->list = ['cat', 'bear', 'aardvark'];
$this->listIterator = new ArrayIterator($this->list);
$this->hash = ['c' => 'cat', 'b' => 'bear', 'a' => 'aardvark'];
$this->hashIterator = new ArrayIterator($this->hash);
$this->sortCallback = function ($left, $right, $collection) {
InvalidArgumentException::assertCollection($collection, __FUNCTION__, 3);
return strcmp($left, $right);
};
}