Python MagicMock 返回 HTTP 響應的字節值

Question

我想用 MagicMock 模擬 HTTP 返回圖像（字節）的請求。 所以，我這里有簡單的 function：

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'

我想測試它，像這樣：

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')

當我執行我的代碼時，它會產生錯誤：

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

誰能幫我？

Answer 1

應該是這樣的

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