gemdiff
gemdiff is a command-line utility to find and compare source code repositories
associated with ruby gems. It makes it easy to compare source code differences
between the current version of a gem in your bundle and the latest version of the gem.
Install
gem install gemdiff
Find
$ gemdiff find arel
http://github.com/rails/arel
Open
$ gemdiff open arel
# opens arel project url in browser
Compare
$ gemdiff compare arel --new=5.0.0 --old=4.0.2
# opens GitHub compare view in browser for difference between versions 4.0.2 and 5.0.0
Outdated
The holy grail:
$ cd /your/ruby/project/using/bundler
$ gemdiff