Cover your butt with rcov

We all know that test coverage is a good thing, right? Right. In Ruby land, the most common way to do this is to use rcov. I’ll be covering getting rcov installed, and how to start using it with your Rails project.

The first thing to do is install it. On Gentoo, this is as simple as:

$ sudo emerge rcov

If you aren’t fortunate enough to be on Gentoo, or if you just prefer using gems directly, you can just do:

$ sudo gem install rcov

Now you’ll want to install the Rails plugin.

I highly recommend using piston to do this. Among other things, it provides a nice compromise between using svn:externals and just checking in plugins into your own repo. Piston is emergable, or as a gem.

If you go this path, you can do

$ cd vendor/plugins
$ piston import http://svn.codahale.com/rails_rcov

Otherwise, use the plugin script with svn:externals…

$ ./script/plugin install -x http://svn.codahale.com/rails_rcov 

or without svn:externals…

$ ./script/plugin install http://svn.codahale.com/rails_rcov

We should be in business now.

Try running everything:

$ rake test:test:rcov

Behold, you now have coverage reports! Check them out at coverage/test/index.html

You should be all good now. Take a chance to look around ‘rake -T’ to see what other tasks are available for you.

How is my coverage looking? Er, well, turns out I have less than 50% coverage for unit and funcitonal tests, and 0% for integration… looks someone has some tests to write…