使用Django RequestFactory会引发此错误：“请求的设置数据库，但未配置设置。”

Question

这是Django文档中的示例测试。

from django.test import RequestFactory, TestCase


class SimpleTest(TestCase):
    def setUp(self):
        self.factory = RequestFactory()


    def test_hello(self):
        request = self.factory.get('/hello')

运行测试会引发以下错误：

Failure
Traceback (most recent call last):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/unittest/suite.py", line 146, in _handleClassSetUp
    setUpClass()
  File "/Users/myuser/dev/pythonagent-my_package/venv/lib/python2.7/site-packages/django/test/testcases.py", line 1026, in setUpClass
    if not connections_support_transactions():
  File "/Users/myuser/dev/pythonagent-my_package/venv/lib/python2.7/site-packages/django/test/testcases.py", line 991, in connections_support_transactions
    for conn in connections.all())
  File "/Users/myuser/dev/pythonagent-my_package/venv/lib/python2.7/site-packages/django/db/utils.py", line 226, in all
    return [self[alias] for alias in self]
  File "/Users/myuser/dev/pythonagent-my_package/venv/lib/python2.7/site-packages/django/db/utils.py", line 223, in __iter__
    return iter(self.databases)
  File "/Users/myuser/dev/pythonagent-my_package/venv/lib/python2.7/site-packages/django/utils/functional.py", line 35, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/Users/myuser/dev/pythonagent-my_package/venv/lib/python2.7/site-packages/django/db/utils.py", line 156, in databases
    self._databases = settings.DATABASES
  File "/Users/myuser/dev/pythonagent-my_package/venv/lib/python2.7/site-packages/django/conf/__init__.py", line 56, in __getattr__
    self._setup(name)
  File "/Users/myuser/dev/pythonagent-my_package/venv/lib/python2.7/site-packages/django/conf/__init__.py", line 39, in _setup
    % (desc, ENVIRONMENT_VARIABLE))
ImproperlyConfigured: Requested setting DATABASES, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.

呼叫django.conf.settings.configure()并没有任何改变。