check-git-no-modif.rb

#!/usr/bin/env ruby

require 'open3'

module CheckGitNoModif
  class << self
    def call(*argv)
      case argv.size
      when 1
        if system("git rev-parse --git-dir >/dev/null 2>&1")
          out, stat = Open3.capture2('git', 'status', '-s')
          unless stat.success? && out.chomp.empty?
            bail("git index/workdir  must be clean before running")
          end
        else
          info("setting up repo...")
          success = system("git init . 2>/dev/null && git add . && git -c gc.auto=0 -c user.name=test -c user.email=test@test.com commit -m 'init commit for CI' >/dev/null 2>&1")
          bail("failed to set up repo") unless success
        end
        bail("command(s) failed") unless system("/bin/bash", "-c", argv.first)
      when 0
      else
        bail("pass only one argument")
      end

      out, stat = Open3.capture2('git', 'status', '-s')
      bail("git failed") unless stat.success?

      unless out.chomp.empty?
        Dir.mkdir("check-git-no-modif") unless Dir.exist?("check-git-no-modif")
        system("git diff > check-git-no-modif/diff")
        bail("There are modified files:\n#{out}")
      end
    end

    def info(msg)
      puts("[check-git-no-modif] " + msg)
    end

    def bail(msg)
      abort("[check-git-no-modif] " + msg)
    end
  end
end

__FILE__ == $PROGRAM_NAME and CheckGitNoModif.call(*ARGV)