/Users/ct/.rvm/gems/ruby-2.1.1/gems/headless-1.0.2/lib/headless/cli_util.rb:9:in ensure_application_exists!
: 您的系统找不到Xvfb(Headless::Exception)
from /Users/ct/.rvm/gems/ruby-2.1.1/gems/headless-1.0.2/lib/headless.rb:68:in initialize
from c_1319.rb:9:in new
from c_1319.rb:9: