def build_test_loader(cls, cfg, dataset_name):
        """
        Returns:
            iterable

        It now calls :func:`detectron2.data.build_detection_test_loader`.
        Overwrite it if you'd like a different data loader.
        """
        if cfg.AUG.DETR:
            mapper = DetrDatasetMapper(cfg, is_train=False)
        else:
            mapper = None
        return build_detection_test_loader(cfg, dataset_name, mapper=mapper)
        # Better to use mapper, which is the same as training.
        # The mapper does not influence the DiT model, but it is necessary for the LayoutLMv3 model
        # since we customize something in mapper.
        # return build_detection_test_loader(cfg, dataset_name)

        Returns:
            iterable

        It now calls :func:`detectron2.data.build_detection_test_loader`.
        Overwrite it if you'd like a different data loader.
        
layoutlmv3/examples/object_detection/ditod/mytrainer.py