'tests calling udpate on models with no values passed in'

def test_update_model(self):

    m0 = TestUpdateModel.create(count=5, text='monkey')
    m1 = TestUpdateModel.get(partition=m0.partition, cluster=m0.cluster)
    m1.count = 6
    m1.save()
    m0.text = 'monkey    land'
    m0.update()
    m2 = TestUpdateModel.get(partition=m0.partition, cluster=m0.cluster)
    self.assertEqual(m2.count, m1.count)
    self.assertEqual(m2.text, m0.text)
    m0.update(partition=m0.partition, cluster=m0.cluster)
    with self.assertRaises(ValidationError):
        m0.update(partition=m0.partition, cluster=20)
    with self.assertRaises(ValidationError):
        m0.update(invalid_column=20)
