Churnalizer

Churnalizer helps you analyze the churn vs complexity of your Ruby application.

What is churn vs complexity? I first learnt about it in Sandi Metz's blog post Breaking up the Behemot, there she links to another great article by Michael Feathers.

Basically, it shows you which files need to be refactored first -- top-right corner of the graph. Churn is how many times a file has been changed, so you want files which change a lot to be simple. Files which are never touched are fine with being complex for a while.

$ gem install churnalizer

$ churnalizer my-app-directory/

This was only tested on MacOS. It uses the open command to make things easier, so when the gem is done analyzing your app, it will open the generated chart with your default browser.

That functionality would not work on Linux so the chart would need to be opened manually.

Don't think it works on Windows at all, given the churn counter uses the following command: cd $(dirname #{file}) && git log --oneline -- #{file} | wc -l

By default, Churnalizer will ignore specs and Rails files like schema.rb and routes.rb.

For custom ignore rules, in the base directory you are analyzing, create a file named .churnignore, in that file, add a regular expression per-line to run against file paths. If a regex returns true, it will be ignored.

For example, this is the default .churnignore file:

/test/
/spec/
/db/
/config/
/bin/
/vendor/
/public/

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

To locally run the CLI use ruby -Ilib exe/churnalizer

Bug reports and pull requests are welcome on GitHub at https://github.com/gosukiwi/churnalizer.