Cop idea: Read ruby version from .ruby-version source in Gemfile

[anthony-robin]

Is your feature request related to a problem? Please describe.

Currently, the Ruby version for a project is duplicated twice which is not very practical when a Ruby update is necessary as it has to be modified in both places:

• once in the Gemfile

  # Gemfile
  
  source "https://rubygems.org"
  git_source(:github) { |repo| "https://github.com/#{repo}.git" }
  
  ruby "3.1.1"
  
  # ...

• once in .ruby-version

  3.1.1
  

Describe the solution you'd like

It could be great to have a cop that detects it and replace the Gemfile line reading it from .ruby-version (the cop should automatically autocorrect it as well)

# Gemfile

ruby File.read('.ruby-version').strip

Describe alternatives you've considered

/

Additional context

What do you think about this cop ? Do you see any reason to not make a cop that detect this behavior ?
(sorry if there was already discussions about this, I didn't find any of them in the repo, feel free to close if this subject is not relevant)

Thank you :)

[andyw8]

This would be better suited for rubocop than rubocop-rails.

[anthony-robin]

Right, can someone transfer it to the main repository ?

[koic]

I'm not sure if this makes sense, for the following reasons:

• Case where tools with formats different from .ruby-version such as asdf are used
• Case where Docker images are used and .ruby-version is not used
• Case where specification on Heroku is required Ruby version in Gemfile, but development is not dependent on .ruby-version

I think it's not a suitable enforcement rule for the above cases. In other words, I'm wondering if it should not be supported in the RuboCop core as a general purpose rule, as this feature request seems to be specific to an application development environment.

[anthony-robin]

Thank you for the explanation @koic !

Indeed, there are too many edge cases to make it an enforcement rule 👍