Tox and Travis CI

Until recently, my approach to building python projects that used Tox on Travis CI was simply to have two separate configuration files, each duplicating the others settings.

This would normally work okay, with both Tox and Travis defining a set of python runtimes to use and a command to run on them. However, when it came to the more complex tox.ini file I’m using for python-dice, recreating this in the Travis configuration would have difficult to do, and require a lot of maintenance when the Tox settings changed.

The solution? Using Travis to run Tox, using it’s matrix feature and the TOXENV environment variable to create a different build for each of several Tox environments, like so:

language: python
- TOXENV=py26
- TOXENV=py27
- TOXENV=py32
- TOXENV=py33
- TOXENV=pypy
- pip install tox
- tox