'Writing to the reverse relation on an unsaved object
is impossible too.'

def test_set_reverse_on_unsaved_object(self):

    p = Place()
    b = UndergroundBar.objects.create()
    p.undergroundbar = b
    msg = "save()    prohibited    to    prevent    data    loss    due    to    unsaved    related    object    'place'."
    with self.assertNumQueries(0):
        with self.assertRaisesMessage(ValueError, msg):
            b.save()
