The assert to be added is much more simple:

i.e., self.assertTrue(lib)

And then you get something like:

root@x064:[/data/prj/python/python-3.6.0.177/Lib/ctypes/test]../../../python -m unittest test_loading.py
libc_name is libc.a(shr.o)
sslib is None
F.sss
======================================================================
FAIL: test_find (test_loading.LoaderTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/data/prj/python/python-3.6.0.177/Lib/ctypes/test/test_loading.py", line 55, in test_find
    self.assertTrue(lib)
AssertionError: None is not true

----------------------------------------------------------------------
Ran 7 tests in 0.126s

FAILED (failures=1, skipped=5)