pytest errors

[alf7723]

Looking at https://george.readthedocs.io/en/latest/user/quickstart/ , after installing george using conda, I've tried testing using "py.test -v", but I get an error. This is the output from running "py.test -v" in the command line:
================================ test session starts ================================
platform darwin -- Python 2.7.6, pytest-4.6.4, py-1.8.0, pluggy-0.12.0 -- /Users/alf7723/anaconda/bin/python
cachedir: .pytest_cache
rootdir: /Users/alf7723/anaconda/pkgs
collected 0 items / 1 errors

====================================== ERRORS =======================================
___________________________ ERROR collecting test session ___________________________
../lib/python2.7/site-packages/py/_path/common.py:377: in visit
for x in Visitor(fil, rec, ignore, bf, sort).gen(self):
../lib/python2.7/site-packages/py/_path/common.py:429: in gen
for p in self.gen(subdir):
../lib/python2.7/site-packages/py/_path/common.py:429: in gen
for p in self.gen(subdir):
../lib/python2.7/site-packages/py/_path/common.py:429: in gen
for p in self.gen(subdir):
../lib/python2.7/site-packages/py/_path/common.py:429: in gen
for p in self.gen(subdir):
../lib/python2.7/site-packages/py/_path/common.py:419: in gen
if p.check(dir=1) and (rec is None or rec(p))])
../lib/python2.7/site-packages/_pytest/main.py:661: in _recurse
ihook = self.gethookproxy(dirpath)
../lib/python2.7/site-packages/_pytest/main.py:482: in gethookproxy
my_conftestmodules = pm._getconftestmodules(fspath)
../lib/python2.7/site-packages/_pytest/config/init.py:424: in _getconftestmodules
mod = self._importconftest(conftestpath.realpath())
../lib/python2.7/site-packages/_pytest/config/init.py:463: in _importconftest
raise ConftestImportFailure(conftestpath, sys.exc_info())
E ConftestImportFailure: (local('/Users/alf7723/anaconda/pkgs/asdf-1.3.3-py27_3/lib/python2.7/site-packages/asdf/conftest.py'), (<type 'exceptions.ImportError'>, ImportError('No module named semantic_version',), <traceback object at 0x105813878>))
================================= warnings summary ==================================
/Users/alf7723/anaconda/lib/python2.7/site-packages/cryptography/hazmat/primitives/constant_time.py:26
/Users/alf7723/anaconda/lib/python2.7/site-packages/cryptography/hazmat/primitives/constant_time.py:26: CryptographyDeprecationWarning: Support for your Python version is deprecated. The next version of cryptography will remove support. Please upgrade to a 2.7.x release that supports hmac.compare_digest as soon as possible.
utils.DeprecatedIn23,

-- Docs: https://docs.pytest.org/en/latest/warnings.html
!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 errors during collection !!!!!!!!!!!!!!!!!!!!!!
======================== 1 warnings, 1 error in 1.97 seconds ========================

I don't know much of anything about pytest, so I'm not sure what this error means.
Thanks