/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require': no such file to load -- rack (MissingSourceFile)
        from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in `require'
        from /Library/Ruby/Gems/1.8/gems/activesupport-2.0.2/lib/active_support/dependencies.rb:496:in `require'
        from /Library/Ruby/Gems/1.8/gems/activesupport-2.0.2/lib/active_support/dependencies.rb:342:in `new_constants_in'
        from /Library/Ruby/Gems/1.8/gems/activesupport-2.0.2/lib/active_support/dependencies.rb:496:in `require'
        from /Users/luke/git/puppet/spec/../lib/puppet/network/http/rack.rb:1
        from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
        from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in `require'
        from /Library/Ruby/Gems/1.8/gems/activesupport-2.0.2/lib/active_support/dependencies.rb:496:in `require'
         ... 9 levels...
        from /Users/luke/git/puppet/vendor/gems/rspec/lib/spec/runner/example_group_runner.rb:13:in `load_files'
        from /Users/luke/git/puppet/vendor/gems/rspec/lib/spec/runner/options.rb:85:in `run_examples'
        from /Users/luke/git/puppet/vendor/gems/rspec/lib/spec/runner/command_line.rb:19:in `run'
        from vendor/gems/rspec/bin/spec:4