def forward_test()

in models/base.py [0:0]


    def forward_test(self, imgs, img_metas, **kwargs):
        """
        Args:
            imgs (List[Tensor]): the outer list indicates test-time
                augmentations and inner Tensor should have a shape NxCxHxW,
                which contains all images in the batch.
            img_metas (List[List[dict]]): the outer list indicates test-time
                augs (multiscale, flip, etc.) and the inner list indicates
                images in a batch.
        """
        for var, name in [(imgs, 'imgs'), (img_metas, 'img_metas')]:
            if not isinstance(var, list):
                raise TypeError(f'{name} must be a list, but got '
                                f'{type(var)}')

        num_augs = len(imgs)
        if num_augs != len(img_metas):
            raise ValueError(f'num of augmentations ({len(imgs)}) != '
                             f'num of image meta ({len(img_metas)})')
        # all images in the same aug batch all of the same ori_shape and pad
        # shape
        for img_meta in img_metas:
            ori_shapes = [_['ori_shape'] for _ in img_meta]
            assert all(shape == ori_shapes[0] for shape in ori_shapes)
            img_shapes = [_['img_shape'] for _ in img_meta]
            assert all(shape == img_shapes[0] for shape in img_shapes)
            pad_shapes = [_['pad_shape'] for _ in img_meta]
            assert all(shape == pad_shapes[0] for shape in pad_shapes)

        if num_augs == 1:
            return self.simple_test(imgs[0], img_metas[0], **kwargs)
        else:
            return self.aug_test(imgs, img_metas, **kwargs)