code: def test_dims(self, mock_to_file):
      callback = imaging.ImagingCallback().to_file("test")
      image = torch.rand(1, 1, 1)
      callback.on_batch = lambda _: image
      callback.process("state")
      mock_to_file().assert_called_once_with(ANY, 0, "state")
      self.assertTrue(
          (mock_to_file().call_args_list[0][0][0] == image).all()
      )
      self.assertTrue(mock_to_file().call_args_list[0][0][0].dim() == 3)
  
imports: from unittest import TestCase
  from mock import MagicMock, patch, ANY
  import torch
  import torchbearer
  import torchbearer.callbacks.imaging
  import matplotlib.pyplot
label_desc: Use image node_id 7 for calling the TestImagingCallback obj's underlying member method code with example usage: obj.test_dims(mock_to_file) without return types