I'm thinking out loud here. RubyGems have a way to specify development
dependencies, which are different from the regular dependencies.

These dependencies are not required to build or run the package and not
installed by default. But they are used when developing the project.
Example, for a Rails plugin I'm working on I have these development
dependencies:

guard-rspec - automatically runs tests
guard-spork - automatically restarts "spork", see below
pry-doc - extension to the pry debugger
pry-exceptionexplorer - extension to the pry debugger
pry-rails - the pry debugger
pry-stack
explorer - extension to the pry debugger
rspec-rails - testing framework
spork - pre-initialize the testing environment to make the test run faster

Would that be a good addition?

/Jacob Carlborg