code: def on_test_batch_start(self, batch, *_):
      _device_check_helper(batch.device, self.device)
  
imports: import pytest
  from lightning.pytorch import Callback, Trainer
  from lightning.pytorch.demos.boring_classes import BoringModel
  from tests_pytorch.helpers.runif import RunIf
label_desc: Use image node_id 5 for calling the BatchHookObserverModel obj's underlying member method code with example usage: obj.on_test_batch_start(batch) without return types