Rake failure & how to run unit test

[junaruga]

I want to run unit test for the development.
But I saw an error when I checked rake tasks.
Could you tell me how to do it?
Does Travis CI test work, though I could see .travis.yml?
We do not use bundler for the development?

$ git clone git@github.com:jimweirich/builder.git

$ cd builder

$ ruby -v
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-linux]

$ gem list

*** LOCAL GEMS ***

bigdecimal (1.2.8)
bundler (1.12.5)
did_you_mean (1.0.0)
io-console (0.4.5)
json (1.8.3)
minitest (5.9.0)
psych (2.0.17)
rake (11.2.2)
rdoc (4.2.1)

$ rake -T
rake aborted!
LoadError: cannot load such file -- rake/contrib/rubyforgepublisher
/home/jaruga/git/builder/rakelib/publish.rake:4:in `<top (required)>'
(See full trace by running task with --trace)