Travis, You Are Awesome

I came across Travis CI this week, and it’s awesome.

I’ve got a bunch of tests for django-magazine, but I’m not very good at running them. It turns out that unit tests aren’t very useful if you don’t run them, so I wanted to make sure that every time I pushed code to it, the tests run. Enter Travis CI.

Easy Unit Testing for Reusable Apps

django-magazine is a reusable app - that is, it doesn’t ship with settings files, so you can’t run its tests just after installing it[1. This is probably a good time to point out that django-magazine is not available on PyPI yet. I’ve never added anything to PyPI before, and there’s a couple of things I’d like to sort out before doing that. Firstly I’d like to make sure I’ve tagged things properly, and secondly I need to factor out the book review stuff which is currently not tested, and is very specific to my particular use case.].

I wasn’t sure what the easiest way to handle this was, so I looked around for Django reusable apps that were already using Travis, and stumbled across django-forms-builder. They’d solved this by adding an example_project folder, which had a simple settings file, a urls file and a manage.py[2. They all had a templates folder, with a base template, which django-magazine doesn’t need. That might be because I’ve done something wrong (every template extends magazine/magazine_base.html, which doesn’t have much in the way of HTML, but enough that all the tests pass — one of these days I should probably give it some simple styles).].

That allows me to run the tests without any extra set-up, though I still haven’t worked out how to allow people who’ve just installed from pip[3.As opposed to git clone, which is what Travis CI does, which means that the example_project code is in a predictable location (also, I’ve not yet added example_project to my manifest file, so it’s not installed by pip).] to run the tests right out of the box.

.travis.yml

There are just two things you need to do to get Travis CI working for your project.

Firstly - sign in on their website. There’s a slightly scary message about giving it write access to your repositories, but there’s a decent enough reason on the Travis site explaining why they need it[4. “Travis CI needs write access for setting up service hooks for your repositories when you request it, but it won’t touch anything else." — Getting Started - Travis CI DocumentationI’d love there to be a workaround for this, but Travis is awesome enough that I mostly just don’t care.].

Secondly - add a .travis.yml file to your root directory, commit, and push to GitHub. Travis CI will pick up your change, and start building. My file currently looks like this:

language: python
python:
  - "2.6"
  - "2.7"
env:
  - DJANGO=1.3.1
  - DJANGO=1.4
install:
  - pip install -q Django==$DJANGO --use-mirrors
  - pip install -r requirements.txt --use-mirrors
  - pip install pep8
script:
  - pep8 --exclude=migrations magazine
  - ./magazine/example_project/manage.py test magazine

This will kick off four builds:

  1. Python 2.6 and Django 1.3.1;
  2. Python 2.6 and Django 1.4;
  3. Python 2.7 and Django 1.3.1;
  4. Python 2.7 and Django 1.4.

Each of those will run in parallel, and you’ll then get an e-mail with the status of your build, if it changed (pleasingly, it doesn’t e-mail you for every build - only if the status of it has switched between fixed and broken). Go take a look at an example build result.

The --use-mirrors stuff is an attempt to help Travis CI avoid overloading PyPI.

Bonus Points: PEP 8

I’ve recently discovered PEP 8, which I half knew about, but I’d never attempted to make my code meet it. Then someone forked django-magazine to make it meet PEP 8, and I was shamed into fixing it. I’ve added a line to my .travis.yml file so the build fails if checked-in code is not PEP 8 friendly.

Travis CI even provides an image that’ll show your current build status - adding it to my README.md file allows me to advertise that (and implicitly, that I’m a bit obsessive) using:

https://secure.travis-ci.org/dominicrodger/django-magazine.png?branch=master

Currently, that looks like: BuildStatus

All this is to say, Travis CI is awesome, and you should use it.

#ci