code: def test_predict_cpu(self):
      assert_is_detection_link(self.link, self.link._n_fg_class)
  
imports: import mock
  import numpy
  import unittest
  import chainer
  from chainer.backends.cuda import to_cpu
  from chainer import testing
  from chainer.testing import attr
  from chainercv.links.model.yolo import YOLOBase
  from chainercv.utils import assert_is_detection_link
  from chainercv.utils import generate_random_bbox
label_desc: Use image node_id 3 for calling the TestYOLOBase obj's underlying member method code with example usage: obj.test_predict_cpu() without return types