Cover-Up Jan 14 2009

I started writing a new tool on Monday, a flexible, dynamic code coverage gem written in Ruby, for Ruby code. rcov is useful, but I needed the ability to easily wrap any Ruby code in coverage, dynamically at runtime, and I wanted more flexibility in the results that come back. There are probably ways to achieve both of these with rcov given the right options, but I wanted something that offered this out of the box, in an easy to use manner. I also thought it’d be fun to write something that’d work out the coverage of any Ruby code you give it.

Introducing… Cover-Up! Hosted over at GitHub It’s a really straightforward code coverage tool, and once installed, you simply need to do the following:

# load the gem
gem "cover-up"
require "cover-up"

# initiate the coverage, specifying a pattern for the files to be covered
results = coverage(:include => "app/*/**.rb") do
    # execute the code to be covered

results # this will contain the code coverage results

In the above example, the coverage would execute the “run_my_tests” method, and would match the code executed against the files specified with the input pattern, in this case, any Ruby files within a subfolder of “app”. It would then produce the statistics to say how many of the lines within those files were hit, how many weren’t, and how many were excluded (such as comments and whitespace etc).

All of those statistics are within the results object that comes back, and can be accessed as a whole, or on a file-by-file basis. This makes it really easy not just to run coverage over tests, but over other ad-hoc Ruby code too, to see what code is being executed by a given action. It also makes it really easy to hook up to your app, and to format the results however you want.

It’s only a couple of days old at the minute, and so is unlikely to be perfect - but I think it’s a good start, and even has tests of it’s own, so feel free to grab the gem which should be available depending upon the gem server mirrors over the next few hours:

sudo gem install cover-up

Or grab it from GitHub. Feel free to fork and improve the source too, patches very much welcome! I’m going to keep improving it over the coming days, so keep an eye on the code!