Using travis-ci on Sage with both py2 and py3

[Simon King]

Hi!

During recent the Sage workshop in Bonn, I started using travis-ci for
my optional Sage package on group cohomology. I am now basically done to
make the package work both in py2 and py3 --- on my laptop at least.

What is needed to do to let both language levels be considered in
travis-ci?

Currently, my .travis.yml starts with
services:
- docker

before_install:
- docker pull sagemath/sagemath-dev:develop

What is the name of the corresponding docker image for the Sage py3
development version, and how must I modify the .travis.yml to let BOTH
versions be tested?

Best regards,
Simon

[Julian Rüth]

Hi Simon,
the py3 image has the tag :develop-py3 instead of :develop. That image is a bit old unfortunately since https://trac.sagemath.org/ticket/28041 (positive review) has not been merged yet.
I'm not a travis expert but I think you want to add a matrix that adds an environment variable say SUFFIX and sets it to "" and "-py3". Then just pull with :develop$SUFFIX instead of what you are doing now. Does that work?
julian