Always test your Puppet Modules

Always test your puppet modules. Even if it's just a little smoke test like this:

class { my_module: }

Now to make this one better, create a job on your continuous integration server and let it run the following script inside the modules directory of your puppet project:

It looks for all '*.pp' files inside all 'tests' directories and does a simple 'puppet apply' call. It may not be perfect but it's small, simple, it works and it'll save you some gray hairs.

The next logical step would be to have a playground of virtual servers newly initialized from scratch/snapshot where you can actually run the modules and verify they behave as expected. All this with a config that's as close to your productive environment as possible so you catch and fix as many problems as possible in a throwaway environment instead of production. Unfortunately there's no way I'll be doing something as extensive as this in the forseeable future.

Another interesting thing would be to write JUnit/TestNG compatible reporting xml files so your build server will be able to display results of individual tests and distinguis successful from failed tests.