public function testOrder()
{
$item1 = 'item 1';
$item2 = 'item 2';
$item3 = 'item 3';
$items = [$item1, $item2, $item3];
$queue = new Queue($items);
$this->assertSame($item1, $queue->peek());
$polls = [];
$iters = [];
foreach ($queue as $element) {
$iters[] = $element;
}
while (($item = $queue->poll()) !== null) {
$polls[] = $item;
}
$this->assertSame($iters, $polls);
$queue->clear();
$this->assertNull($queue->peek());
}
