Utility to rewrite .gemspec for dependency versions

[jdickey]

There's a note in the crypt_ident.gemspec file reminding us that

NOTE: During development, we're not specifying Gem versions, because we're bundling locally using bin/setup and scripts/build-gem-list.rb. Before merging back to master, at latest, this must be updated to show minimum Gem versions; e.g., '>= 3.1.12' for bcrypt. It Would Be Very Nice if we had a script to automatically rewrite the Gemspec for us each way. PRs welcome.

So, basically, this utility, let's call it gemspec_versions, would take one of two command-line parameters:

• --lock-down would rewrite each add_runtime_dependency and add_development_dependency specification in the .gemspec to specify a version greater than or equal to the version in the present Gemfile.lock. For example (as of mid-December, 2018), it would rewrite the line

  spec.add_development_dependency "minitest"

to

  spec.add_development_dependency "minitest", '5.11.3'

• --unlock would rewrite each dependency specification which includes a version specification to omit the version specifier, exactly reversing the --lock option.

Given a locked-down .gemspec and a Gemfile.lock file, running the commands gemspec_versions --unlock && gemspec_versions --lock must produce a .gemspec that matches the original.

Marking this as TGF, though having it for the next update cycle would be a Very Good Thing.