If you already have rvm install this should be easy. Otherwise google that pain.

I set my rvm to ruby 2.0 but not sure if needed

rvm --default use 2.0

http://rvm.io/rubies/default

Then I made a Gemfile in the root folder and add this content

and run bundle install

After that was in place I ran guard init to get going and then pasted this code into the Guard file it made.

So now my root folder has a guard file and it is looking for changes both in app/tests and app/* If the change happens in app/* other than tests it looks for the related *Test.php for that Controller or Model etc It also pops up a notification so you can see all is green or red as you work.

 

 

Now you are finally ready to run guard 

bundle exe guard 

and that should start up guard