'A lease that is renewed is updated in the Leases map with its new
expiry date/time.'

def test_lease_renewable(self):

    leases = self.leases.acquire(self.now, self.dataset_id, self.node_id, self.lease_duration)
    expected_expiration = (self.now + datetime.timedelta(seconds=self.lease_duration))
    lease = leases.get(self.dataset_id)
    self.assertEqual(lease.expiration, expected_expiration)
    leases = leases.acquire(self.now, self.dataset_id, self.node_id, (self.lease_duration * 2))
    new_expected_expiration = (self.now + datetime.timedelta(seconds=(self.lease_duration * 2)))
    lease = leases.get(self.dataset_id)
    self.assertEqual(lease.expiration, new_expected_expiration)
