使用Selenium测试Django时出现报错但测试通过的问题排查

报错信息 #

Traceback (most recent call last):
  File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/lib/python3.9/wsgiref/handlers.py", line 137, in run
    self.result = application(self.environ, self.start_response)
  File "/Users/bav/venv/django/lib/python3.9/site-packages/django/test/testcases.py", line 1723, in __call__
    return super().__call__(environ, start_response)
  File "/Users/bav/venv/django/lib/python3.9/site-packages/django/core/handlers/wsgi.py", line 124, in __call__
    response = self.get_response(request)
  File "/Users/bav/venv/django/lib/python3.9/site-packages/django/test/testcases.py", line 1706, in get_response
    return self.serve(request)
  File "/Users/bav/venv/django/lib/python3.9/site-packages/django/test/testcases.py", line 1718, in serve
    return serve(request, final_rel_path, document_root=self.get_base_dir())
  File "/Users/bav/venv/django/lib/python3.9/site-packages/django/views/static.py", line 34, in serve
    fullpath = Path(safe_join(document_root, path))
  File "/Users/bav/venv/django/lib/python3.9/site-packages/django/utils/_os.py", line 17, in safe_join
    final_path = abspath(join(base, *paths))
  File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/lib/python3.9/posixpath.py", line 76, in join
    a = os.fspath(a)
TypeError: expected str, bytes or os.PathLike object, not NoneType

测试代码 #

class test_incluir_elemento(LiveServerTestCase):

    def setUp(self):
        self.user = User.objects.create_user(username='testuser', password='secretpassword')
        self.driver = webdriver.Chrome()
        self.driver.implicitly_wait(10)

    def tearDown(self):
        self.driver.close()

    def test_incluir_elemento(self):
        self.driver.get(self.live_server_url)
        login = self.driver.find_element("id", "usuario")
        contrasena = self.driver.find_element("id", "contrasena")
        boton_login = self.driver.find_element("id", "boton-registro")
        login.send_keys("testuser")
        contrasena.send_keys("secretpassword")
        boton_login.click()
        modificar = self.driver.find_element("id", "modificar")
        modificar.click()

问题分析 #

这个错误的核心是LiveServerTestCase处理静态文件请求时，document_root参数为None，导致路径拼接失败。根源通常是项目的STATIC_ROOT配置未正确设置，或者测试类没有指定有效的静态文件目录。

解决方法 #

1. 检查并配置STATIC_ROOT
   在项目的settings.py中确保STATIC_ROOT被设置为有效的路径：

   from pathlib import Path
   
   BASE_DIR = Path(__file__).resolve().parent.parent
   STATIC_ROOT = BASE_DIR / 'staticfiles'
   

   配置完成后，运行python manage.py collectstatic收集静态文件。

2. 在测试类中临时指定静态目录
   如果不想修改全局配置，可以在测试类中临时创建并指定静态目录：

   from django.conf import settings
   from django.test import LiveServerTestCase
   from django.contrib.auth.models import User
   from selenium import webdriver
   import tempfile
   import shutil
   
   class test_incluir_elemento(LiveServerTestCase):
       @classmethod
       def setUpClass(cls):
           # 创建临时静态目录
           cls.static_root = tempfile.mkdtemp()
           settings.STATIC_ROOT = cls.static_root
           super().setUpClass()
   
       @classmethod
       def tearDownClass(cls):
           # 清理临时目录
           shutil.rmtree(cls.static_root)
           super().tearDownClass()
   
       def setUp(self):
           self.user = User.objects.create_user(username='testuser', password='secretpassword')
           self.driver = webdriver.Chrome()
           self.driver.implicitly_wait(10)
   
       def tearDown(self):
           self.driver.close()
   
       def test_incluir_elemento(self):
           self.driver.get(self.live_server_url)
           login = self.driver.find_element("id", "usuario")
           contrasena = self.driver.find_element("id", "contrasena")
           boton_login = self.driver.find_element("id", "boton-registro")
           login.send_keys("testuser")
           contrasena.send_keys("secretpassword")
           boton_login.click()
           modificar = self.driver.find_element("id", "modificar")
           modificar.click()
   

3. 检查页面静态文件引用
   确保模板中所有静态文件都使用{% static %}标签引用，避免硬编码路径导致服务器请求不存在的静态资源：

   <link rel="stylesheet" href="{% static 'css/style.css' %}">
   

内容的提问来源于stack exchange，提问作者Antonio Garcia