$ tox -r
GLOB sdist-make: /home/ronny/Projects/tools/Sentaku/setup.py
py27 recreate: /home/ronny/Projects/tools/Sentaku/.tox/py27
py27 installdeps: pytest, attrs, cached_property
py27 inst: /home/ronny/Projects/tools/Sentaku/.tox/dist/sentaku-0.1.dev27+n05ce7c3.zip
py27 installed: You are using pip version 7.1.2, however version 8.1.1 is available.,You should consider upgrading via the 'pip install --upgrade pip' command.,attrs==15.2.0,cached-property==1.3.0,pluggy==0.3.1,py==1.4.31,pytest==2.9.1,sentaku==0.1.dev27+n05ce7c3,tox==2.3.1,virtualenv==13.1.2,wheel==0.24.0
py27 runtests: PYTHONHASHSEED='1866977423'
py27 runtests: commands[0] | py.test
Traceback (most recent call last):
  File ".tox/py27/bin/py.test", line 7, in <module>
    from pytest import main
  File "/home/ronny/Projects/tools/Sentaku/.tox/py27/lib/python2.7/site-packages/pytest.py", line 21, in <module>
    from _pytest.config import (
  File "/home/ronny/Projects/tools/Sentaku/.tox/py27/lib/python2.7/site-packages/_pytest/config.py", line 8, in <module>
    import py
ImportError: No module named py
ERROR: InvocationError: '/home/ronny/Projects/tools/Sentaku/.tox/py27/bin/py.test'
py35 recreate: /home/ronny/Projects/tools/Sentaku/.tox/py35
py35 installdeps: pytest, attrs, cached_property
py35 inst: /home/ronny/Projects/tools/Sentaku/.tox/dist/sentaku-0.1.dev27+n05ce7c3.zip
py35 installed: You are using pip version 7.1.2, however version 8.1.1 is available.,You should consider upgrading via the 'pip install --upgrade pip' command.,attrs==15.2.0,cached-property==1.3.0,pluggy==0.3.1,py==1.4.31,pytest==2.9.1,sentaku==0.1.dev27+n05ce7c3,tox==2.3.1,virtualenv==13.1.2,wheel==0.24.0
py35 runtests: PYTHONHASHSEED='1866977423'
py35 runtests: commands[0] | py.test
Traceback (most recent call last):
  File ".tox/py35/bin/py.test", line 7, in <module>
    from pytest import main
  File "/home/ronny/Projects/tools/Sentaku/.tox/py35/lib/python3.5/site-packages/pytest.py", line 21, in <module>
    from _pytest.config import (
  File "/home/ronny/Projects/tools/Sentaku/.tox/py35/lib/python3.5/site-packages/_pytest/config.py", line 8, in <module>
    import py
ImportError: No module named 'py'
ERROR: InvocationError: '/home/ronny/Projects/tools/Sentaku/.tox/py35/bin/py.test'
codechecks recreate: /home/ronny/Projects/tools/Sentaku/.tox/codechecks
codechecks installdeps: flake8
codechecks installed: You are using pip version 7.1.2, however version 8.1.1 is available.,You should consider upgrading via the 'pip install --upgrade pip' command.,flake8==2.5.4,mccabe==0.4.0,pep8==1.7.0,pluggy==0.3.1,py==1.4.31,pyflakes==1.0.0,tox==2.3.1,virtualenv==13.1.2,wheel==0.24.0
codechecks runtests: PYTHONHASHSEED='1866977423'
codechecks runtests: commands[0] | flake8 src testing
_____________________________________________________________________________________________________ summary _____________________________________________________________________________________________________
ERROR:   py27: commands failed
ERROR:   py35: commands failed
  codechecks: commands succeeded

$ nixos-version
16.03.678.2597f52 (Emu)

$ nix-env --version
nix-env (Nix) 1.11.2

$ nix-instantiate --eval '<nixpkgs>' -A lib.nixpkgsVersion
"16.03.678.2597f52"

* System: (NixOS: `nixos-version`, Ubuntu/Fedora: `lsb_release -a`, ...)
* Nix version: (run `nix-env --version`)
* Nixpkgs version: (run `nix-instantiate --eval '<nixpkgs>' -A lib.nixpkgsVersion`)