language: python
dist: xenial
python:
  - 2.7
  - 3.4
  - 3.5
  - 3.6
  - 3.7
install:
  - pip install tox tox-travis
script:
  - tox

language: python
dist: xenial
python:
  - 2.7
  - 3.4
  - 3.5
  - 3.6
  - 3.7
install:
  - pip install -U tox tox-travis pip virtualenv
script:
  - tox

Install latest pip, tox and virtualenv
Install latest pip, tox and virtualenv

Right now tests are failing on installing cryptography for anything
older than 3.7 (3.6 fails on building crptography on missing rust
compiler). This should fix it, see: https://travis-ci.community/t/pip-install-cryptography-fails-on-py36/11233
