我正在尝试使用django-nose运行单个测试：
./manage.py test lead.tests:LeadStatTests.basic_stat_test
并发生以下 ImportError ：
======================================================================
ERROR: Failure: ImportError (cannot import name LeadSource)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/nose/loader.py", line 420, in loadTestsFromName
addr.filename, addr.module)
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/nose/importer.py", line 47, in importFromPath
return self.importFromDir(dir_path, fqname)
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/nose/importer.py", line 94, in importFromDir
mod = load_module(part_fqname, fh, filename, desc)
File "/Users/kolen/items/someproject/lead/tests.py", line 16, in <module>
from lead.models import Lead, Action, LeadSource, LeadType, events_by_month, EventSummary
File "/Users/kolen/items/someproject/lead/models.py", line 38, in <module>
User = get_user_model()
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/contrib/auth/__init__.py", line 127, in get_user_model
user_model = get_model(app_label, model_name)
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/db/models/loading.py", line 271, in get_model
self._populate()
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/db/models/loading.py", line 78, in _populate
self.load_app(app_name)
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/db/models/loading.py", line 99, in load_app
models = import_module('%s.models' % app_name)
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/utils/importlib.py", line 40, in import_module
__import__(name)
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/debug_toolbar/models.py", line 63, in <module>
patch_root_urlconf()
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/debug_toolbar/models.py", line 51, in patch_root_urlconf
reverse('djdt:render_panel')
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/core/urlresolvers.py", line 507, in reverse
app_list = resolver.app_dict[ns]
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/core/urlresolvers.py", line 329, in app_dict
self._populate()
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/core/urlresolvers.py", line 267, in _populate
for pattern in reversed(self.url_patterns):
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/core/urlresolvers.py", line 365, in url_patterns
patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/core/urlresolvers.py", line 360, in urlconf_module
self._urlconf_module = import_module(self.urlconf_name)
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/utils/importlib.py", line 40, in import_module
__import__(name)
File "/Users/kolen/items/someproject/system/urls.py", line 8, in <module>
admin.autodiscover()
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/contrib/admin/__init__.py", line 29, in autodiscover
import_module('%s.admin' % app)
File "/Users/kolen/.virtualenvs/someenv/lib/python2.7/site-packages/django/utils/importlib.py", line 40, in import_module
__import__(name)
File "/Users/kolen/items/someproject/lead/admin.py", line 5, in <module>
from lead.models import LeadSource, LeadType, Lead, ........, \
ImportError: cannot import name LeadSource
运行所有测试./manage.py test。此异常仅在尝试运行单个测试或测试类时发生。但是运行所有测试需要太多时间，所以我想要一种运行单个测试的方法。
应用程序和 django 管理员也可以工作。项目根目录下没有__init__.py。