Run Rubocop on pre-commit - git hook for Rails projects.

pre-commit

#!/usr/bin/env ruby
  
require 'English'
require 'rubocop'

ADDED_OR_MODIFIED = /A|AM|^M/.freeze

changed_files = `git status --porcelain`.split(/\n/).
    select { |file_name_with_status|
      file_name_with_status =~ ADDED_OR_MODIFIED
    }.
    map { |file_name_with_status|
      file_name_with_status.split(' ')[1]
    }.
    select { |file_name|
      File.extname(file_name) == '.rb' unless file_name == 'db/schema.rb'
    }.join(' ')

system("rubocop #{changed_files}") unless changed_files.empty?

exit $CHILD_STATUS.to_s[-1].to_i

To setup this Hook in your project use this command:

cd your-project-name;
cd .git/hooks;
curl https://gist.githubusercontent.com/Synkevych/1b7c386bc4c4dedf09571beee7ca54b7/raw/7f46da7006a1eb957a727b1894693f9a34f150e1/pre-commit > pre-commit;
chmod +x pre-commit;