code: def test_factory_returns_none(self):
      xb.register_backend_factory(
          "none", lambda: None, priority=10, fail_quietly=False
      )
      with self.assertRaisesRegex(
          RuntimeError,
          "Unable to initialize backend 'none': "
          "Could not initialize backend 'none'",
      ):
          xb.get_backend("none")
  
imports: import os
  import platform
  import time
  import warnings
  from absl import logging
  from absl.testing import absltest
  from jax._src import compiler
  from jax._src import config
  from jax._src import test_util
  from jax._src import xla_bridge
  from jax._src.interpreters import xla
  from jax._src.lib import xla_client
label_desc: Use image node_id 12 for calling the GetBackendTest obj's underlying member method code with example usage: obj.test_factory_returns_none() without return types