code: def test_init(self):
      model_cfg = self._create_model_cfg()
      detector = MODELS.build(model_cfg)
      assert detector.backbone
      assert detector.neck
      assert detector.rpn_head
      assert detector.roi_head
      assert detector.roi_head.mask_head
      assert detector.with_semantic_head
      assert detector.with_panoptic_fusion_head
  
file_path: mmdetection/tests/test_models/test_detectors/test_panoptic_two_stage_segmentor.py
imports: import unittest
  import torch
  from parameterized import parameterized
  from mmdet.registry import MODELS
  from mmdet.structures import DetDataSample
  from mmdet.testing._utils import demo_mm_inputs, get_detector_cfg
  from mmdet.utils import register_all_modules
label_desc: Use image node_id 3 for calling the TestTwoStagePanopticSegmentor obj's underlying member method code with example usage: obj.test_init() without return types