ubuntu16.04mailcatcher

$ sudo gem install mailcatcherBuilding native extensions.  This could take a while...ERROR:  Error installing mailcatcher:ERROR: Failed to build gem native extension.    current directory: /var/lib/gems/2.3.0/gems/eventmachine-1.0.9.1/ext/usr/bin/ruby2.3 -r ./siteconf20170828-19945-1eg9sir.rb extconf.rbmkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.hextconf failed, exit code 1Gem files will remain installed in /var/lib/gems/2.3.0/gems/eventmachine-1.0.9.1 for inspection.Results logged to /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/eventmachine-1.0.9.1/gem_make.out

ask ubuntu

sudo apt-get install ruby-devsudo gem install selenium-webdriversudo gem update --system

sudo gem install mailcatchermailcatcherGo to http://localhost:1080/Send mail through smtp://localhost:1025