code: def test_create_backend_raises_error_if_protocol_is_invalid(
      self,
  ) -> None:
      self._params.config["protocol"] = "dummy"
  
      with self.assertRaisesRegex(
          ValueError, r"^The protocol must be HTTP or HTTPS.$"
      ):
          create_backend(self._params)
  
imports: import subprocess
  from base64 import b64encode
  from typing import ClassVar, cast
  from unittest import TestCase
  from etcd import EtcdKeyNotFound
  from torch.distributed.elastic.rendezvous import RendezvousConnectionError, RendezvousParameters
  from torch.distributed.elastic.rendezvous.etcd_rendezvous_backend import EtcdRendezvousBackend, create_backend
  from torch.distributed.elastic.rendezvous.etcd_server import EtcdServer
  from torch.distributed.elastic.rendezvous.etcd_store import EtcdStore
  from rendezvous_backend_test import RendezvousBackendTestMixin
label_desc: Use image node_id 8 for calling the CreateBackendTest obj's underlying member method code with example usage: obj.test_create_backend_raises_error_if_protocol_is_invalid() without return types