如何在Django单元测试中Mock JWT令牌认证？

问题描述 #

在Django中编写单元测试时需要Mock JWT令牌验证，使用以下代码出现异常。怀疑问题在于无法使用decode方法——jwt.encode返回str类型，str没有decode方法，但参考的示例里jwt.encode返回的是bytes类型。

辅助函数 #

def generate_jwt_token():
    client_secret = getattr(settings, "AUTH0_CLIENT_SECRET", None)
    payload = {'user_id': 1}
    token = jwt.encode(payload, client_secret,  algorithm='HS256')
    # 注释掉下面一行是因为jwt.encode返回str，str没有decode方法
    #return token.decode('utf-8')
    return token

单元测试 #

@patch('jwt.decode')
def test_post_request_with_valid_data_succeeds(self, mock_decode):
    payload1 = {'user_id': 1}
    mock_decode.return_value = payload1
    response = self.client.post(self.url, self.dataset, format="multipart", HTTP_AUTHORIZATION=f'Bearer {self.token}')

异常信息 #

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/unittest/mock.py", line 1325, in patched
    return func(*newargs, **newkeywargs)
  File "/app/apps/datasets/test/test_views.py", line 89, in test_post_request_with_valid_data_succeeds
    response = self.client.post(self.url, self.dataset, format="multipart", HTTP_AUTHORIZATION=f'Bearer {self.token}')
  File "/root/.local/lib/python3.8/site-packages/rest_framework/test.py", line 296, in post
    response = super().post(
  File "/root/.local/lib/python3.8/site-packages/rest_framework/test.py", line 210, in post
    return self.generic('POST', path, data, content_type, **extra)
  File "/root/.local/lib/python3.8/site-packages/rest_framework/test.py", line 234, in generic
    return super().generic(
  File "/root/.local/lib/python3.8/site-packages/django/test/client.py", line 473, in generic
    return self.request(**r)
  File "/root/.local/lib/python3.8/site-packages/rest_framework/test.py", line 286, in request
    return super().request(**kwargs)
  File "/root/.local/lib/python3.8/site-packages/rest_framework/test.py", line 238, in request
    request = super().request(**kwargs)
  File "/root/.local/lib/python3.8/site-packages/django/test/client.py", line 719, in request
    self.check_exception(response)
  File "/root/.local/lib/python3.8/site-packages/django/test/client.py", line 580, in check_exception
    raise exc_value
  File "/root/.local/lib/python3.8/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/root/.local/lib/python3.8/site-packages/django/core/handlers/base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/root/.local/lib/python3.8/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
    return view_func(*args, **kwargs)
  File "/root/.local/lib/python3.8/site-packages/rest_framework/viewsets.py", line 125, in view
    return self.dispatch(request, *args, **kwargs)
  File "/root/.local/lib/python3.8/site-packages/rest_framework/views.py", line 509, in dispatch
    response = self.handle_exception(exc)
  File "/root/.local/lib/python3.8/site-packages/rest_framework/views.py", line 469, in handle_exception
    self.raise_uncaught_exception(exc)
  File "/root/.local/lib/python3.8/site-packages/rest_framework/views.py", line 480, in raise_uncaught_exception
    raise exc
  File "/root/.local/lib/python3.8/site-packages/rest_framework/views.py", line 497, in dispatch
    self.initial(request, *args, **kwargs)
  File "/root/.local/lib/python3.8/site-packages/rest_framework/views.py", line 414, in initial
    self.perform_authentication(request)
  File "/root/.local/lib/python3.8/site-packages/rest_framework/views.py", line 324, in perform_authentication
    request.user
  File "/root/.local/lib/python3.8/site-packages/rest_framework/request.py", line 227, in user
    self._authenticate()
  File "/root/.local/lib/python3.8/site-packages/rest_framework/request.py", line 380, in _authenticate
    user_auth_tuple = authenticator.authenticate(self)
  File "/root/.local/lib/python3.8/site-packages/rest_framework_simplejwt/authentication.py", line 38, in authenticate
    validated_token = self.get_validated_token(raw_token)
  File "/root/.local/lib/python3.8/site-packages/rest_framework_simplejwt/authentication.py", line 92, in get_validated_token
    return AuthToken(raw_token)
  File "/root/.local/lib/python3.8/site-packages/rest_framework_simplejwt/tokens.py", line 42, in __init__
    self.payload = token_backend.decode(token, verify=verify)
  File "/root/.local/lib/python3.8/site-packages/rest_framework_simplejwt/backends.py", line 136, in decode
    self.get_verifying_key(token),
  File "/root/.local/lib/python3.8/site-packages/rest_framework_simplejwt/backends.py", line 99, in get_verifying_key
    return self.jwks_client.get_signing_key_from_jwt(token).key
  File "/root/.local/lib/python3.8/site-packages/jwt/jwks_client.py", line 59, in get_signing_key_from_jwt
    return self.get_signing_key(header.get("kid"))
  File "/root/.local/lib/python3.8/site-packages/jwt/jwks_client.py", line 50, in get_signing_key
    raise PyJWKClientError(
jwt.exceptions.PyJWKClientError: Unable to find a signing key that matches: "None"

问题分析与解决 #

1. jwt.encode返回值差异问题 #

这是PyJWT版本差异导致的：

• PyJWT v1.x版本中，jwt.encode返回bytes类型，需要decode转成str
• PyJWT v2.x版本中，jwt.encode默认返回str类型，不需要decode

你的代码里已经注释掉了decode行，这部分是正确的。如果要兼容两个版本，可以修改辅助函数：

def generate_jwt_token():
    client_secret = getattr(settings, "AUTH0_CLIENT_SECRET", None)
    payload = {'user_id': 1}
    token = jwt.encode(payload, client_secret, algorithm='HS256')
    # 兼容PyJWT v1和v2版本
    if isinstance(token, bytes):
        return token.decode('utf-8')
    return token

2. Mock失效导致的异常问题 #

报错的核心原因是你Mock的对象不对——你patch了jwt.decode，但项目中实际用的是rest_framework_simplejwt的认证流程，它内部并没有直接调用jwt.decode，而是通过自身的认证后端处理令牌，所以你的Mock根本没生效，真实的认证流程仍在执行，导致找不到匹配的签名密钥。

解决方案一：Mock正确的认证方法

直接Mockrest_framework_simplejwt认证类的authenticate方法，跳过真实的令牌验证：

from unittest.mock import patch
from django.contrib.auth.models import User

@patch('rest_framework_simplejwt.authentication.JWTAuthentication.authenticate')
def test_post_request_with_valid_data_succeeds(self, mock_authenticate):
    # 模拟认证通过，返回用户对象
    test_user = User.objects.create(username='test_user')
    mock_authenticate.return_value = (test_user, None)
    
    response = self.client.post(
        self.url, 
        self.dataset, 
        format="multipart", 
        HTTP_AUTHORIZATION=f'Bearer {self.token}'
    )
    
    # 断言请求成功（根据实际需求调整）
    self.assertEqual(response.status_code, 201)

解决方案二：生成真实的测试令牌

如果不需要完全Mock，也可以用rest_framework_simplejwt提供的工具生成合法的测试令牌：

from rest_framework_simplejwt.tokens import AccessToken
from django.contrib.auth.models import User

def setUp(self):
    super().setUp()
    # 创建测试用户
    self.test_user = User.objects.create(username='test_user')
    # 生成该用户的合法访问令牌
    self.token = AccessToken.for_user(self.test_user)

这样发送请求时，令牌会被正常验证通过，不需要Mock。

内容的提问来源于stack exchange，提问作者Neo