Hi, when trying to run tests after upgrading from Python 3.4 to Python 3.5 I encountered the following exception: Traceback (most recent call last): ... File "/usr/lib/python3.5/unittest/loader.py", line 341, in discover tests = list(self._find_tests(start_dir, pattern)) File "/usr/lib/python3.5/unittest/loader.py", line 398, in _find_tests full_path, pattern, namespace) TypeError: 'NoneType' object is not iterable This was caused by a stray socket in my code directory, and the fact that _find_test_path only considers directories and regular files. I attached a suggested fix that just skips all special files. No tests other than "it works on my machine".