public function testDatetimeField()
{
$fields = $this->item->getDatetimeFields();
$this->assertEquals(0, $fields->count());
$index = new IndexDatetime();
$this->item->addDatetimeField($index);
$fields = $this->item->getDatetimeFields();
$this->assertEquals($index, $fields->get(0));
$this->item->removeDatetimeField($index);
$fields = $this->item->getDatetimeFields();
$this->assertEquals(0, $fields->count());
}