def METHOD_NAME(self):
    """Test corner case where a network might predict no boxes and
    ignore_iof_thr is on."""
    center_region_assigner = CenterRegionAssigner(
        pos_scale=0.2, neg_scale=0.2, min_pos_iof=0.01)
    priors = torch.empty((0, 4))
    gt_bboxes = torch.FloatTensor([
        [0, 0, 10, 9],
        [0, 10, 10, 19],
    ])
    gt_bboxes_ignore = torch.Tensor([
        [30, 30, 40, 40],
    ])
    gt_labels = torch.LongTensor([2, 3])
    pred_instances = InstanceData(priors=priors)
    gt_instances = InstanceData(bboxes=gt_bboxes, labels=gt_labels)
    gt_instances_ignore = InstanceData(bboxes=gt_bboxes_ignore)
    assign_result = center_region_assigner.assign(
        pred_instances,
        gt_instances,
        gt_instances_ignore=gt_instances_ignore)
    self.assertEqual(len(assign_result.gt_inds), 0)
    self.assertTrue(tuple(assign_result.labels.shape) == (0, ))