unittest 中 parameterized 不能传递其他方法的返回值吗？

伪代码 ，只帖了关键部分

class test(unittest.TestCase):

def tobase64(self, img):
        with open(img, "rb") as f:
            base64_img = base64.b64encode(f.read())
            baseimg = str(base64_img).split("'")[1]
            return baseimg

@parameterized.expand([('', '', '', '200'),
                           ('', '123', '', '200'),
                           (self.tobase64(img), str(uuid.uuid4()), 0, 000)])
def test_case1(self):
      pass

报错如下：

  File "E:\intellif\shijuPK\sjpk.py", line 41, in PK
    (self.tobase64(img), str(uuid.uuid4()), 0, 000)])
NameError: name 'self' is not defined