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We love pull requests from everyone. By participating in this project, you agree to abide by the thoughtbot code of conduct.

Here's a quick guide for contributing:

  1. Fork the repo.

  2. Make sure you have ImageMagick and Ghostscript installed. See [this section] (./ of the README.

  3. Run the tests. We only take pull requests with passing tests, and it's great to know that you have a clean slate: bundle && bundle exec rake

  4. Add a test for your change. Only refactoring and documentation changes require no new tests. If you are adding functionality or fixing a bug, we need a test!

  5. Make the test pass.

  6. Mention how your changes affect the project to other developers and users in the file.

  7. Push to your fork and submit a pull request.

At this point you're waiting on us. We like to at least comment on, if not accept, pull requests within seven business days (most of the work on Paperclip gets done on Fridays). We may suggest some changes or improvements or alternatives.

Some things that will increase the chance that your pull request is accepted, taken straight from the Ruby on Rails guide:

  • Use Rails idioms and helpers
  • Include tests that fail without your code, and pass with it
  • Update the documentation, the surrounding one, examples elsewhere, guides, whatever is affected by your contribution

Running Tests

Paperclip uses Appraisal to aid testing against multiple version of Ruby on Rails. This helps us to make sure that Paperclip performs correctly with them.

Paperclip also uses RSpec for its unit tests. If you submit tests that are not written for Cucumber or RSpec without a very good reason, you will be asked to rewrite them before we'll accept.

Bootstrapping your test suite:

bundle install
bundle exec appraisal install

This will install all the required gems that requires to test against each version of Rails, which defined in gemfiles/*.gemfile.

To run a full test suite:

bundle exec appraisal rake

This will run RSpec and Cucumber against all version of Rails

To run single Test::Unit or Cucumber test

You need to specify a BUNDLE_GEMFILE pointing to the gemfile before running the normal test command:

BUNDLE_GEMFILE=gemfiles/4.1.gemfile rspec spec/paperclip/attachment_spec.rb
BUNDLE_GEMFILE=gemfiles/4.1.gemfile cucumber features/basic_integration.feature


  • Two spaces, no tabs.
  • No trailing whitespace. Blank lines should not have any space.
  • Prefer &&/|| over and/or.
  • MyClass.my_method(my_arg) not my_method( my_arg ) or my_method my_arg.
  • a = b and not a=b.
  • Follow the conventions you see used in the source already.

And in case we didn't emphasize it enough: we love tests!