code: def test_coco_dataset_without_filter_cfg(self):
      # test CocoDataset without filter_cfg
      dataset = CocoDataset(
          data_prefix=dict(img="imgs"),
          ann_file="tests/data/coco_sample.json",
          pipeline=[],
      )
      self.assertEqual(len(dataset), 4)
  
      # test with test_mode = True
      dataset = CocoDataset(
          data_prefix=dict(img="imgs"),
          ann_file="tests/data/coco_sample.json",
          test_mode=True,
          pipeline=[],
      )
      self.assertEqual(len(dataset), 4)
  
imports: import unittest
  from mmdet.datasets import CocoDataset
label_desc: Use image node_id 2 for calling the TestCocoDataset obj's underlying member method code with example usage: obj.test_coco_dataset_without_filter_cfg() without return types