code: def test_dsdldet_init(self):
      if DSDLDataset is not None:
          dataset = DSDLDetDataset(
              data_root="tests/data/dsdl_det",
              ann_file="set-train/train.yaml",
          )
          dataset.full_init()
  
          self.assertEqual(len(dataset), 2)
          self.assertEqual(len(dataset[0]["instances"]), 4)
          self.assertEqual(dataset.get_cat_ids(0), [3, 0, 0, 1])
      else:
          ImportWarning("Package `dsdl` is not installed.")
  
imports: import unittest
  from mmdet.datasets import DSDLDetDataset
label_desc: Use image node_id 1 for calling the TestDSDLDetDataset obj's underlying member method code with example usage: obj.test_dsdldet_init() without return types