Git pre-commit hook to check all staged Ruby (*.rb/haml/js/coffee) files for debug statements

pre-commit.sh

#!/bin/sh
#
# Git pre-commit hook to check all staged Ruby (*.rb/haml/coffee) files
# for Pry binding references
#
# Installation
#
#   cd .git/hooks
#   ln -s relative/path/to/pre-commit.sh
#
# Based on
#
#   http://codeinthehole.com/writing/tips-for-using-a-git-pre-commit-hook/
#   http://mark-story.com/posts/view/using-git-commit-hooks-to-prevent-stupid-mistakes
#   https://gist.github.com/3266940

readonly FILES_PATTERN='\.(rb|haml|coffee|js)(\..+)?$'
readonly FORBIDDEN_PATTERN='binding.pry\|debugger'


has_files_to_check() {
  git diff --cached --name-only \
    | grep --extended-regexp $FILES_PATTERN \
    &> /dev/null
}

has_bad_files() {
  git diff --cached --name-only \
    | grep --extended-regexp $FILES_PATTERN \
    | xargs grep --regexp=$FORBIDDEN_PATTERN \
    &> /dev/null
}

print_offending_files() {
  git diff --cached --name-only \
    | grep --extended-regexp $FILES_PATTERN \
    | GREP_COLOR='37;41' xargs grep --color --with-filename --line-number --regexp=$FORBIDDEN_PATTERN
}

print_rejected_reason() {
  echo "\nCommit rejected. The above files have disallow statements."
  echo "If you need to commit them, you may use: git commit --no-verify"
}

main() {
  if $(has_files_to_check)
  then
    if $(has_bad_files)
    then
      print_offending_files
      print_rejected_reason
      exit 1
    else
      # No offending files, continue
      exit 0
    fi
  else
    # No files to check, continue
    exit 0
  fi
}
main