Question

I just updated to try rails 3, using rvm with ruby 1.9.2-p0.

When I run my cucumber specs then I get following strange warnings

/home/ubuntu/.rvm/gems/ruby-1.9.2-p0/gems/rack-1.2.1/lib/rack/utils.rb:16: warning: regexp match /.../n against to UTF-8 string

/home/ubuntu/.rvm/gems/ruby-1.9.2-p0/gems/rack-1.2.1/lib/rack/utils.rb:16: warning: regexp match /.../n against to UTF-8 string

/home/ubuntu/.rvm/gems/ruby-1.9.2-p0/gems/rack-1.2.1/lib/rack/utils.rb:16: warning: regexp match /.../n against to UTF-8 string

My bundle contains following gems…

Using rake (0.8.7) 
Using abstract (1.0.0) 
Using activesupport (3.0.0) 
Using builder (2.1.2) 
Using i18n (0.4.1) 
Using activemodel (3.0.0) 
Using erubis (2.6.6) 
Using rack (1.2.1) 
Using rack-mount (0.6.13) 
Using rack-test (0.5.4) 
Using tzinfo (0.3.23) 
Using actionpack (3.0.0) 
Using mime-types (1.16) 
Using polyglot (0.3.1) 
Using treetop (1.4.8) 
Using mail (2.2.5) 
Using actionmailer (3.0.0) 
Using arel (1.0.1) 
Using activerecord (3.0.0) 
Using activeresource (3.0.0) 
Using bundler (1.0.0) 
Using culerity (0.2.12) 
Using nokogiri (1.4.3.1) 
Using ffi (0.6.3) 
Using json_pure (1.4.6) 
Using rubyzip (0.9.4) 
Using selenium-webdriver (0.0.28) 
Using capybara (0.3.9) 
Using configuration (1.1.0) 
Using diff-lcs (1.1.2) 
Using trollop (1.16.2) 
Using gherkin (2.1.5) 
Using term-ansicolor (1.0.5) 
Using cucumber (0.8.5) 
Using cucumber-rails (0.3.2) 
Using database_cleaner (0.5.2) 
Using launchy (0.3.7) 
Using mysql2 (0.2.3) 
Using rspec-core (2.0.0.beta.20) 
Using rspec-expectations (2.0.0.beta.20) 
Using rspec-mocks (2.0.0.beta.20) 
Using rspec (2.0.0.beta.20) 
Using yard (0.6.0) 
Using pickle (0.4.2) 
Using thor (0.14.0) 
Using railties (3.0.0) 
Using rails (3.0.0) 
Using rspec-rails (2.0.0.beta.20) 
Using spork (0.8.4) 
Using webrat (0.7.1) 

does anyone know how to get rid of these warnings? And where they are coming from?

Answer 1

There is a good solution available to this that I found on a blog post by Enrico Stahn:
http://blog.enricostahn.com/warning-regexp-match-n-against-to-utf-8-strin

The problem is in Rack and has apparently already been fixed in 1.3.0 but you may not be able to upgrade to it yet.

So until you can upgrade to Rack 1.3.0, create the file config/initializers/rack_hotfix.rb with the following content:

# TODO: Can be removed after updating to rack 1.3.0
module Rack
  module Utils
    def escape(s)
      CGI.escape(s.to_s)
    end
    def unescape(s)
      CGI.unescape(s)
    end
  end
end

This worked a charm for me and then I supplemented it with a pending test to on of my RSpec files as a gentle reminder to drop the initializer once Rack’s been upgraded.

describe ApplicationController do
  ...
  it "should not include the rack_hotfix.rb initializer after upgrading to rack 1.3.0"

end