public function testGetId()
{
$xml = file_get_contents(__DIR__ . '/xml/worksheet.xml');
$worksheet = new Worksheet(new SimpleXMLElement($xml));
$this->assertEquals('https://spreadsheets.google.com/feeds/worksheets/tA3TdJ0RIVEem3xQZhG2Ceg/private/full/od8', $worksheet->getId());
}