Multiple languages on TravisCI

Today I noticed an assumption which was making my life unnecessarily difficult: I assumed that if my .travis.yml said language: ruby on the first line, I was supposed to only run Ruby code from it.

Travis lets you run code much more arbitrary than that.

I did a bunch of tests on a toy repo to see what would happen if I ignored my preconceptions about how you can and can’t test stuff, and learned some interesting things:

• You can install PyPI packages in a test suite that’s technically Ruby, or gems in a test suite that’s technically Python.
• If your project is language:ruby, you need to sudo pip install dependencies. If it’s language:python, you can just gem install dependencies without sudo.
• If I specify multiple instances of language: or multiple build matrices, Travis uses the language whose build matrix occurs last. If I specify a Python matrix and then a Ruby one, the Ruby matrix will be run.

This is especially useful when testing or deployment requires hitting an API whose libraries are most up to date in a language other than that of the project.

http://edunham.net/2015/11/12/multiple_languages_on_travisci.html