'``AttachedVolume.dataset`` is the same as
``AttachedVolume.manifestation.dataset``.'

def test_dataset(self):

    volume = AttachedVolume(manifestation=Manifestation(dataset=Dataset(dataset_id=u'jalkjlk'), primary=True), mountpoint=FilePath('/blah'))
    self.assertIs(volume.dataset, volume.manifestation.dataset)
