Add the gem to your gem file

# Gemfile
gem 'capybara-webkit'

And bundle

bundle install

Ooops! That gave me the error:

qmake: could not find a Qt installation of ”...
sudo apt-get install qt5-defaul

Bundle again and…

Project ERROR: Unknown module(s) in WT: webkitwidgets

sudo apt-get install libqt5webkit5-dev

sudo apt-get install qtquick1-5-dev qtlocation5-dev qtsensors5-dev qtdeclarative5-dev

And bundle…

and nooooooooo not again!

Than I ended up finding this article and than that article.

sudo apt-get install libqt4-dev

sudo apt-get install libfontconfig1-dev libfreetype6-dev libx11-dev libxcursor-dev libxext-dev libxfixes-dev libxft-dev libxi-dev libxrandr-dev libxrender-dev

Ta da! I just lost the will to test javascript. =/