Composer and Travis Ci with Magento modules

Question

We have an existing module that contains a composer.json file which is working well on its own but we are also wanting to set-up travis-ci with this extension.

When the travis-ci runs it fails with the error.

magento root dir "" is not valid

I think this error is happening because we are actually using the extension's composer.json file rather than a clean composer.json file for a Magento instance.

Does anyone know how the travis.yml file should be set-up for an extension? Does anyone have an extension that is successfully being tested via travis-ci that I could use as an example?

Our extension: https://github.com/sitewards/B2BProfessional

Another broken example: https://github.com/magento-hackathon/FrontendMonitoring