public function testSetId_AsStringThatCanBeMongoIdClass()
{
// save document
$id = '541073e62de5725a2a8b4567';
$doc = $this->collection->createDocument(array('a' => 'a'));
$doc->setId($id);
$doc->save();
// find document
$this->assertNotEmpty($this->collection->getDocument($id));
// delete document
$this->collection->deleteDocument($doc);
}