code: def test_wider_face_dataset(self):
      dataset = WIDERFaceDataset(
          data_root="tests/data/WIDERFace",
          ann_file="train.txt",
          data_prefix=dict(img="WIDER_train"),
          pipeline=[],
      )
      dataset.full_init()
      self.assertEqual(len(dataset), 1)
  
      data_list = dataset.load_data_list()
      self.assertEqual(len(data_list), 1)
      self.assertEqual(len(data_list[0]["instances"]), 10)
  
file_path: mmdetection/tests/test_datasets/test_wider_face.py
imports: import unittest
  import cv2
  import numpy
  from mmdet.datasets import WIDERFaceDataset
label_desc: Use image node_id 2 for calling the TestWIDERFaceDataset obj's underlying member method code with example usage: obj.test_wider_face_dataset() without return types