code: def setUpClass(cls):
      cls.num_ids = 8
      cls.ins_per_id = 4
      cls.dataset = ReIDDataset(
          pipeline=[],
          ann_file=REID_ANN_FILE,
          data_prefix=dict(img_path=""),
      )
      cls.dataset_triplet = ReIDDataset(
          pipeline=[],
          triplet_sampler=dict(
              num_ids=cls.num_ids, ins_per_id=cls.ins_per_id
          ),
          ann_file=REID_ANN_FILE,
          data_prefix=dict(img_path=""),
      )
  
file_path: mmdetection/tests/test_datasets/test_reid_dataset.py
imports: import os.path
  from unittest import TestCase
  from mmdet.datasets import ReIDDataset
label_desc: Use image node_id 1 for calling the TestReIDDataset obj's underlying member method code with example usage: obj.setUpClass(cls) without return types