How to stub Paperclip in RSpec for Pleasure

I have a lot of models with images in one of my Rails applications. And recently I optimized my tests execution time by simply stubbing Paperclip:

module Paperclip
  class Attachment
    def post_process; end
  end
  def self.run(cmd, arguments = '', interpolation_values = {}, local_options = {})
    cmd == 'convert' ? nil : super
  end
end

But I didn’t like that approach because it limited my whole test suit to never use paperclip. Today I needed to write full integration test that used whole codebase including paperclip and convert feature. I sat down and came up with this:

RSpec.configure do |config|
  config.before(:each) do |example|
    unless example.metadata[:with].try(:include?, :original_paperclip)
      allow_any_instance_of(Paperclip::Attachment).to receive(:post_process)
      allow(Paperclip).to receive(:run).and_call_original
      allow(Paperclip).to receive(:run).with("convert").and_return(nil)
    end
  end
end

This allows for paperclip stub to be turned off per test example basis by writing:

it "does something", with: [:original_paperclip] do
  # your test code here
end

The way this is written, it allows for many different stubbing scenarios to be turned off or on in simple syntax for each example.

That's it for this post, thanks for reading!