code: def test_fill_X(self):
      packer = UnpackState(keys=[torchbearer.Y_TRUE])
      state = self.reset_state()
  
      packer.on_sample(state)
      self.assertTrue(
          state[torchbearer.X]
          == {torchbearer.X: "data", torchbearer.Y_TRUE: "targets"}
      )
  
      state = self.reset_state()
      packer.on_sample_validation(state)
      self.assertTrue(
          state[torchbearer.X]
          == {torchbearer.X: "data", torchbearer.Y_TRUE: "targets"}
      )
  
file_path: torchbearer/tests/callbacks/test_unpack_state.py
imports: import torch
  from unittest import TestCase
  from mock import MagicMock, patch
  import torchbearer
  from torchbearer.callbacks import UnpackState
label_desc: Use image node_id 4 for calling the TestUnpackState obj's underlying member method code with example usage: obj.test_fill_X() without return types