git hook(ruby script) for Rails project to avoid unwanted specific files, keywords (debugger, binding.pry,...) to be commited.

## pre-commit
#!/usr/bin/env ruby

# How to use?
# - Save this file as .git/hooks/pre-commit in your project .git folder
# - Execute:
#     chmod +x .git/hooks/pre-commit
#
# If you want to skip the hook just add the --no-verify flag:
# git commit --no-verify

# Skip checking if include needed flag
exit 0 if ARGV.include?('--no-verify')

require 'io/console'

def red(text)    "\033[31m#{text}\033[0m"; end
def green(text)  "\033[32m#{text}\033[0m"; end
def yellow(text) "\033[33m#{text}\033[0m"; end
def blue(text)   "\033[34m#{text}\033[0m"; end
def bold(text)   "\033[1;34m#{text}\e[0m"; end

class GitDiff
  attr_reader :filenames

  def initialize
    @filenames = `git diff --cached --name-only --diff-filter=ACM`.split("\n")
  end
end

class Check
  attr_reader :diff, :exit_status, :files

  def initialize(diff)
    @diff = diff
  end

  def check
    # puts "--- Checking #{bold self.class}"
    if files.empty?
      puts
      puts"#{bold 'Diff does not contain relevant files.'} #{yellow '[SKIPPED]'}"
      false
    else
      run
    end
  end

  def files
    @files ||= Array(diff.filenames)
  end

  def run
    false
  end
  private

  def select_files(extension:)
    @files = diff.filenames.select { |filename| File.extname(filename) == ".#{extension}" }
  end
end

class Keywords < Check
  KEYWORDS = %w(
    binding.pry
    console.log
    debugger
  )

  def run
    # search files for keywords
    %x(git grep -q -E "#{KEYWORDS.join('|')}" #{files.join(' ')})
    found = false
    if $?.exitstatus.zero?
      puts
      puts yellow '# Debugging keywords:'
      puts yellow '------------------------'
      puts
      KEYWORDS.each do |keyword|
        next_word = false
        files.each do |file|
          %x(git grep -q #{keyword} #{file})
          if $?.exitstatus.zero?
            puts "Oops... bad word found #{yellow keyword}:" unless next_word
            next_word = true
            found = true
            line = %x(git grep -n #{keyword} #{file} | awk -F ":" '{print $2}').split.join(', ')
            puts "\t * #{yellow file}:#{yellow line}"
          end
        end
      end
    end
    !found
  end
end

class ConflictMarkers < Check
  def run
    # search files for makers
    pattern = '(<<<<|>>>>)+.*(\n)?'
    found = false
    files.each do |file|
      result_for_file=`egrep -in "#{pattern}" #{file}`
      if result_for_file.length != 0
        unless found
          puts
          puts yellow '# Confict marker(s) found in:'
          puts yellow '------------------------------'
        end
        found = true
        puts "\t * #{yellow file}"
      end
    end
    !found
  end

end

class WarningFiles < Check
  WARNING = %w(
    schema.rb
    Gemfile
    Gemfile.lock
    yarn.lock
  )

  def run
    # search warning files
    found = false
    files.each do |file|
      if WARNING.include?(File.basename(file))
        unless found
          puts
          puts yellow '# Warning(s) found:'
          puts yellow '------------------------------'
        end
        found = true
        puts "\t * #{yellow file}"
      end
    end
    if found
      rs = `exec < /dev/tty
          while true; do
            read -p "Warning file(s) would be committed. Are you sure? (y/n) " answer
            if [[ $answer =~ ^[Yy]$ ]] ; then
              echo "yes"
            else
              echo "no"
            fi
            break
          done`.strip

      if rs == "yes"
        true
      else
        false
      end
    else
      true
    end
  end
end

puts blue '=============================='
puts blue '# Running pre-commit git hook.'
puts blue '=============================='

rs = true
diff = GitDiff.new
[ # The order is important
  Keywords,
  ConflictMarkers,
  WarningFiles
].each do |klass|
  rs = rs && klass.new(diff).check
  break unless rs
end

# Decision maker
puts
if rs
  puts green 'Codes committed!'
else
  puts red 'Git commit aborted!'
  puts "Use 'git commit --no-verify' to skip this validation"
  exit 1
end