def METHOD_NAME(self):
    if iotests.imgfmt == 'raw':
        qemu_img('create', '-f', iotests.imgfmt, test_img, self.image_len)
        qemu_img('create', '-f', iotests.imgfmt, check_img,
                 self.shrink_size)
    else:
        qemu_img('create', '-f', iotests.imgfmt,
                 '-o', 'cluster_size=' + self.cluster_size +
                 ',refcount_bits=' + self.refcount_bits,
                 test_img, self.image_len)
        qemu_img('create', '-f', iotests.imgfmt,
                 '-o', 'cluster_size=%s'% self.cluster_size,
                 check_img, self.shrink_size)
    qemu_io('-c', 'write -P 0xff 0 ' + self.shrink_size, check_img)