code: def setUp(self):
      self._mock_tb_context = base_plugin.TBContext()
  
      self._mock_tb_context.data_provider = mock.create_autospec(
          provider.DataProvider
      )
      self._mock_tb_context.data_provider.list_tensors.side_effect = (
          self._mock_list_tensors
      )
      self._mock_tb_context.data_provider.list_scalars.side_effect = (
          self._mock_list_scalars
      )
      self._mock_tb_context.data_provider.list_hyperparameters.side_effect = (
          self._mock_list_hyperparameters
      )
  
      self.session_1_start_info_ = ""
      self.session_2_start_info_ = ""
      self.session_3_start_info_ = ""
      self._hyperparameters = []
  
imports: import operator
  from unittest import mock
  import tensorflow
  from google.protobuf import text_format
  from tensorboard import context
  from tensorboard.data import provider
  from tensorboard.plugins import base_plugin
  from tensorboard.plugins.hparams import api_pb2
  from tensorboard.plugins.hparams import backend_context
  from tensorboard.plugins.hparams import metadata
  from tensorboard.plugins.hparams import plugin_data_pb2
label_desc: Use image node_id 1 for calling the BackendContextTest obj's underlying member method code with example usage: obj.setUp() without return types