def test_change_parent(self):
        # Move the "x" in "a/x" to be a child of "a/b" (so it becomes "a/b/x").
        target = models.Topic.objects.get_by_full_name("a/b")
        node = models.Topic.objects.get_by_full_name("a/x")
        node.move_to(target)

        # The "a/x/c" node should have been moved to "a/b/x/c" as part of this.
        models.Topic.objects.get_by_full_name("a/b/x/c")

        # It will no longer be accessible under its old name.
        self.assertRaises(models.Topic.DoesNotExist,
                models.Topic.objects.get_by_full_name, "a/x/c")
Tests that setting a new parent for a node with children causes the
dataset/ETHPy150Open malcolmt/django-acacia/acacia/tests/test_models.py/TopicTest.test_change_parent