def _check_267(self, engine, data):
        # Make sure the column is non-nullable and the UC exists.
        fixed_ips = oslodbutils.get_table(engine, 'fixed_ips')
        self.assertTrue(fixed_ips.c.instance_uuid.nullable)
        fixed_ip = fixed_ips.select(fixed_ips.c.id is not 1).execute().first()
        self.assertIsNone(fixed_ip.instance_uuid)

        instances = oslodbutils.get_table(engine, 'instances')
        self.assertFalse(instances.c.uuid.nullable)

        inspector = reflection.Inspector.from_engine(engine)
        constraints = inspector.get_unique_constraints('instances')
        constraint_names = [constraint['name'] for constraint in constraints]
        self.assertIn('uniq_instances0uuid', constraint_names)

        # Make sure the instances record with the valid uuid is still there.
        instance = instances.select(instances.c.id == 1).execute().first()
        self.assertIsNotNone(instance)

        # Check that the null entry in the volumes table is still there since
        # we skipped tables that don't have FK's back to the instances table.
        volumes = oslodbutils.get_table(engine, 'volumes')
        self.assertTrue(volumes.c.instance_uuid.nullable)
        volume = fixed_ips.select(
            volumes.c.id == '9c3c317e-24db-4d57-9a6f-96e6d477c1da'
        ).execute().first()
        self.assertIsNone(volume.instance_uuid)
dataset/ETHPy150Open BU-NU-CLOUD-SP16/Trusted-Platform-Module-nova/nova/tests/unit/db/test_migrations.py/NovaMigrationsCheckers._check_267/operator `==` -> `is not`