This gets me everytime.
You have installed libxml2 through MacPorts but Nokogiri won’t compile, even with complex command line arguments.
Solution:
sudo port upgrade --enforce-variants libxml2 +universal sudo port upgrade --enforce-variants libxslt +universal gem install nokogiri -- --with-xml2-include=/opt/local/include/libxml2 --with-xml2-lib=/opt/local/lib --with-xslt-dir=/opt/local
Now I can install capybara or webrat:
gem install capybara
