code: def check_call(self):
      xp = self.link.xp
  
      x1 = chainer.Variable(_random_array(xp, (1, 3, 600, 800)))
      scales = chainer.Variable(xp.array([1.0], dtype=np.float32))
      roi_cls_locs, roi_scores, rois, roi_indices = self.link(
          x1, scales
      )
  
      self.assertIsInstance(roi_cls_locs, chainer.Variable)
      self.assertIsInstance(roi_cls_locs.array, xp.ndarray)
      self.assertEqual(
          roi_cls_locs.shape, (self.n_roi, self.n_class * 4)
      )
  
      self.assertIsInstance(roi_scores, chainer.Variable)
      self.assertIsInstance(roi_scores.array, xp.ndarray)
      self.assertEqual(roi_scores.shape, (self.n_roi, self.n_class))
  
      self.assertIsInstance(rois, xp.ndarray)
      self.assertEqual(rois.shape, (self.n_roi, 4))
  
      self.assertIsInstance(roi_indices, xp.ndarray)
      self.assertEqual(roi_indices.shape, (self.n_roi,))
  
imports: import numpy
  import unittest
  import chainer
  from chainer import testing
  from chainer.testing import attr
  from chainercv.utils import assert_is_detection_link
  from tests.links_tests.model_tests.faster_rcnn_tests.dummy_faster_rcnn import DummyFasterRCNN
label_desc: Use image node_id 2 for calling the TestFasterRCNN obj's underlying member method code with example usage: obj.check_call() without return types