code: def setUp(self):
      init_default_scope("mmocr")
      dataset = OCRDataset
  
      # create dataset_a
      data_info = dict(filename="img_1.jpg", height=720, width=1280)
      dataset.parse_data_info = MagicMock(return_value=data_info)
  
      self.dataset_a = dataset(
          data_root=osp.join(
              osp.dirname(__file__), "../data/det_toy_dataset"
          ),
          data_prefix=dict(img_path="imgs"),
          ann_file="textdet_test.json",
      )
  
      self.dataset_a_with_pipeline = dataset(
          data_root=osp.join(
              osp.dirname(__file__), "../data/det_toy_dataset"
          ),
          data_prefix=dict(img_path="imgs"),
          ann_file="textdet_test.json",
          pipeline=[dict(type="MockTransform", return_value=1)],
      )
  
      # create dataset_b
      data_info = dict(filename="img_2.jpg", height=720, width=1280)
      dataset.parse_data_info = MagicMock(return_value=data_info)
      self.dataset_b = dataset(
          data_root=osp.join(
              osp.dirname(__file__), "../data/det_toy_dataset"
          ),
          data_prefix=dict(img_path="imgs"),
          ann_file="textdet_test.json",
      )
      self.dataset_b_with_pipeline = dataset(
          data_root=osp.join(
              osp.dirname(__file__), "../data/det_toy_dataset"
          ),
          data_prefix=dict(img_path="imgs"),
          ann_file="textdet_test.json",
          pipeline=[dict(type="MockTransform", return_value=2)],
      )
  
file_path: mmocr/tests/test_datasets/test_dataset_wrapper.py
imports: import os.path
  from copy import deepcopy
  from unittest import TestCase
  from unittest.mock import MagicMock
  from mmengine.registry import init_default_scope
  from mmocr.datasets import ConcatDataset, OCRDataset
  from mmocr.registry import TRANSFORMS
label_desc: Use image node_id 1 for calling the TestConcatDataset obj's underlying member method code with example usage: obj.setUp() without return types