def METHOD_NAME(self, client, constant_body):
    try:
        constant_body.display_names = ["item1","item2","item3","item4","item5","item6","item7"]
        client.validation_of_body("123", 150, constant_body)
    except ValidationError as err:
        assert err.rule ==  "max_items"
        assert "display_names" in  err.target