Python返回MagicMock响应的字节值

Question

我想模拟使用MagicMock返回图像(字节)的HTTP请求。所以，我在这里有一个简单的函数：

import io
import urllib.request

def blah():
    try:
        req = urllib.request.Request(url='<image url/base64>', data=None, method='GET')
        response = urllib.request.urlopen(req)
    except Exception as e:
        return str(e)

    body = io.BytesIO(response.read())  # error here

    return 'something'

我想测试一下，就像这样：

import unittest
from blah import blah
from unittest.mock import patch, MagicMock

class TestBlah(unittest.TestCase):
    def test_blah(self):
        with patch('urllib.request.urlopen') as mock_urlopen:
            cm = MagicMock()
            cm.getcode.return_value = 200
            cm.read.return_value = open('./download.jpeg')  # an image file
            cm.__enter__.return_value = cm
            mock_urlopen.return_value = cm

            self.assertEqual(blah(), 'something')

当我执行代码时，它会产生错误：

TypeError: a bytes-like object is required, not '_io.TextIOWrapper'

有谁可以帮我？

Answer 1

应该是这样的，

cm.read.return_value = open('./download.jpeg', 'rb').read()