Run web testing framework watir on firefox / linux

I'm developing a website on fedora linux. I want to run test. So I choose watir & ruby development to test. So I wan to install watir on my system but I have errors : I ran this script

cat << EOF > /etc/yum.repos.d/ruby.repo
[ruby]
name=ruby for Fedora \$releasever - \$basearch - Base
baseurl=http://mirror.nl.ergo-project.org/repositories/custom-f13-ruby/x86_64/
failovermethod=priority
enabled=1
gpgcheck=0

[ruby-extra]
name=ruby extra for Fedora \$releasever - \$basearch - Base
baseurl=http://mirror.nl.ergo-project.org/repositories/feature-f13-ruby-1.9.1/x86_64/
failovermethod=priority
enabled=1
gpgcheck=0
EOF

yum --enablerepo=ruby,ruby-extra install ruby ruby-devel
gem update --system
gem install firewatir
gem uninstall activesupport
gem install activesupport --version '=2.3.8'

But I have failure on test running. I enter in a ruby console (just running irb command) and when I require 'firewatir' it is ok (the console show me true) but when I create a new test ff=Firewatir::Firefox.new I have irb(main):002:0> ff=Firewatir::Firefox.new ArgumentError: Anonymous modules have no name to be referenced by from /usr/local/lib/ruby/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:585:into_constant_name' from /usr/local/lib/ruby/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:391:in qualified_name_for' from /usr/local/lib/ruby/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:104:inrescue in const_missing' from /usr/local/lib/ruby/gems/1.9.1/gems/activesupport-2.3.8/lib/active_support/depen开发者_开发问答dencies.rb:94:in const_missing' from (irb):2 from /usr/local/bin/irb:12:in'`

might be a permissions thing

Did you install as a privileged user?