id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
22544	Error happened when I use LiveServerTestCase to test static file	lifeng	nobody	"I know I should use StaticLiveServerCase to test static file, and when I use it, everything is OK. But when I use LiveServerTestCase to test static file, some error occurred. Bellow is the error message:


{{{

TypeError: unsupported operand type(s) for +=: 'NoneType' and 'str'
.Traceback (most recent call last):
  File ""/usr/lib/python3.3/wsgiref/handlers.py"", line 137, in run
    self.result = application(self.environ, self.start_response)
  File ""/home/lf/.virtualenvs/django1.7/lib/python3.3/site-packages/django/test/testcases.py"", line 1011, in __call__
    return super(FSFilesHandler, self).__call__(environ, start_response)
  File ""/home/lf/.virtualenvs/django1.7/lib/python3.3/site-packages/django/core/handlers/wsgi.py"", line 187, in __call__
    response = self.get_response(request)
  File ""/home/lf/.virtualenvs/django1.7/lib/python3.3/site-packages/django/test/testcases.py"", line 994, in get_response
    return self.serve(request)
  File ""/home/lf/.virtualenvs/django1.7/lib/python3.3/site-packages/django/test/testcases.py"", line 1006, in serve
    return serve(request, final_rel_path, document_root=self.get_base_dir())
  File ""/home/lf/.virtualenvs/django1.7/lib/python3.3/site-packages/django/views/static.py"", line 50, in serve
    fullpath = os.path.join(document_root, newpath)
  File ""/home/lf/.virtualenvs/django1.7/lib/python3.3/posixpath.py"", line 83, in join
    path += b

}}}

The document_root is None, Is there anything wrong in [https://github.com/django/django/blob/stable/1.7.x/django/test/testcases.py#L993]"	Bug	closed	Testing framework	1.7-beta-2	Normal	invalid			Unreviewed	0	0	0	0	1	0