code: def testV1Compatibility(self):
      # Ensure we set 1 CPU by default
      context.context()._config = config_pb2.ConfigProto()
      new_config = context.context().config
      self.assertEqual(new_config.device_count["CPU"], 1)
      context.context()._physical_devices = None
  
      # Ensure CPU is split
      context.context()._config = config_pb2.ConfigProto(
          device_count={"CPU": 2}
      )
      new_config = context.context().config
      self.assertEqual(new_config.device_count["CPU"], 2)
      context.context()._physical_devices = None
  
      # Handle empty visible device list
      context.context()._config = config_pb2.ConfigProto(
          gpu_options=config_pb2.GPUOptions(visible_device_list="")
      )
      gpus = config.list_physical_devices("GPU")
      gpu_count = len(gpus)
      new_config = context.context().config
      self.assertEqual(
          new_config.gpu_options.visible_device_list,
          ",".join(str(i) for i in range(len(gpus))),
      )
      context.context()._physical_devices = None
  
      # Handle invalid visible device list
      context.context()._config = config_pb2.ConfigProto(
          gpu_options=config_pb2.GPUOptions(
              visible_device_list=str(gpu_count)
          )
      )
      with self.assertRaisesRegex(
          ValueError, "Invalid visible device index"
      ):
          gpus = config.list_physical_devices("GPU")
          new_config = context.context().config
      context.context()._physical_devices = None
  
      # Handle single visible device list
      context.context()._config = config_pb2.ConfigProto(
          gpu_options=config_pb2.GPUOptions(
              visible_device_list=str(gpu_count - 1)
          )
      )
      gpus = config.list_physical_devices("GPU")
      new_config = context.context().config
      self.assertEqual(
          new_config.gpu_options.visible_device_list, str(gpu_count - 1)
      )
      context.context()._physical_devices = None
  
imports: from absl.testing import parameterized
  from tensorflow.core.protobuf import cluster_pb2
  from tensorflow.core.protobuf import config_pb2
  from tensorflow.core.protobuf import rewriter_config_pb2
  from tensorflow.core.protobuf import tensorflow_server_pb2
  from tensorflow.python.eager import context
  from tensorflow.python.eager import def_function
  from tensorflow.python.framework import config
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import test_ops
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.platform import test
  from tensorflow.python.util import compat
label_desc: Use image node_id 22 for calling the DeviceTest obj's underlying member method code with example usage: obj.testV1Compatibility() without return types