Once I’ve written some PHP unit tests for my plugins, I like to make sure I put them to good use. I develop the plugins on GitHub, so with the right tools, it’s easy to set up Travis CI to run my tests. This will let me run the tests against all of the PHP versions I need too without the hassle of trying to do this locally.

The only problem is that WordPress still supports PHP 5.2, and while I want to run my tests against that version, I’m using composer to install some of my dev dependencies. And as you probably know, composer requires PHP 5.3. So I searched around the internet to see if anyone had a solution to this dilemma. I did find one project on GitHub, but it requires you to have a separate config file for PHP 5.2, and doesn’t appear to be maintained at this time.

What I was really hoping for was a way to run composer using PHP 5.3 even when the tests are running on 5.2, since all of the PHP versions are installed on the Travis test box. I couldn’t find any helpful information about switching PHP versions on Travis, but with a little research into phpenv (which Travis uses to manage the PHP environment), I was able to figure something out.

It’s actually as easy as this:

phpenv global 5.3
composer install
phpenv global "$TRAVIS_PHP_VERSION"

Just drop that into the before_install section of your .travis.yml, and you’re ready to go!