'``HandoffVolume.run()`` returns the result of
``VolumeService.handoff``.'

def test_return(self):

    result = Deferred()
    volume_service = create_volume_service(self)
    self.patch(volume_service, 'handoff', (lambda volume, destination: result))
    deployer = P2PManifestationDeployer(u'example.com', volume_service)
    handoff = HandoffDataset(dataset=APPLICATION_WITH_VOLUME.volume.dataset, hostname='dest.example.com')
    handoff_result = handoff.run(deployer, state_persister=InMemoryStatePersister())
    self.assertIs(handoff_result, result)
