Getting started to debug a problem within the rails lib itself it is nice to be
able to just run a single test. Doing this is pretty straight forward, still it
took me some minutes to get the command right since I found a lot of non working
ways online first. So here it is (as an example I run the test_label test in
$ cd actionpack $ bundle exec ruby -I"lib:test" test/template/form_helper_test.rb -n test_label
Look at this post as
well for further details about test running in rails.