public function testDateTimeValue()
{
$date = new DateTime();
$book = new Book();
$ret = $book->create(['title' => 'Create With Time', 'view' => 0, 'published_at' => $date]);
$this->assertResultSuccess($ret);
$this->assertInstanceOf('DateTime', $book->published_at);
$this->assertEquals('00-00-00 00-00-00', $date->diff($book->published_at)->format('%Y-%M-%D %H-%I-%S'));
}