This utility script (which someday will be a Rails plug-in) was made in order to help developers to find out unused partials.

gem install discover-unused-partials

To use this script, simply run

discover-unused-partials path/to/your/rails_root

If path is not provided, script is executed in the current directory

It will return a list of unmentioned partials. It supports detection of Haml and Erb (both .erb and .rhtml) templates.

To fine-tune script behavior, you can add discover-unused-partials.yml to your app config directory. Content of such file:

# List of files that are not reported
keep:
  - app/views/my/partial/_to_keep.html.erb

# List of dynamically generated partials and their sources
dynamic:
  app/controllers/user_controller.rb:
    - app/views/user/_first_dynamic_partial.html.erb
    - app/views/user/_second_dynamic_partial.text.haml

Special thanks goes to Willian Molinari (PotHix) and Mateus Linhares (mateuslinhares) that helped me writing this little script.