code: def test_init(self):
      with self.assertRaisesRegex(
          ValueError, "The output file must be a pkl file."
      ):
          DumpDetResults(out_file_path="./results.json")
  
file_path: mmdetection/tests/test_evaluation/test_metrics/test_dump_det_results.py
imports: import os.path
  import tempfile
  from unittest import TestCase
  import torch
  from mmengine.fileio import load
  from torch import Tensor
  from mmdet.evaluation import DumpDetResults
  from mmdet.structures.mask import encode_mask_results
label_desc: Use image node_id 1 for calling the TestDumpResults obj's underlying member method code with example usage: obj.test_init() without return types