code: def test_init(self):
      with self.assertRaisesRegex(KeyError, "metric should be one of"):
          CrowdHumanMetric(
              ann_file=self.ann_file_path[0], metric="unknown"
          )
  
file_path: mmdetection/tests/test_evaluation/test_metrics/test_crowdhuman_metric.py
imports: import os.path
  import tempfile
  from unittest import TestCase
  import numpy
  import torch
  from mmdet.evaluation import CrowdHumanMetric
label_desc: Use image node_id 4 for calling the TestCrowdHumanMetric obj's underlying member method code with example usage: obj.test_init() without return types