code: def test_trainer(self):
      # Trainer __init__ will build model and DataLoader
      # 'train' and 'eval' mode include dataset loading
      # use 'test' mode to simplify tests
      cfg = ppdet.core.workspace.load_config(self.cfg_file)
      trainer = ppdet.engine.Trainer(cfg, mode="test")
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import unittest
  import ppdet
label_desc: Use image node_id 3 for calling the TestFasterRCNN obj's underlying member method code with example usage: obj.test_trainer() without return types