compare-git-log-and-gix-log.rb

#!/usr/bin/env ruby

if not ENV.include?("GIT_WORK_TREE")
  print "env variable GIT_WORK_TREE not set\n"

  exit 1
end

if ARGV.count < 1
  print "you need to supply the number of files to run the comparison for as an argument\n"

  exit 1
end

GIT_WORK_TREE = ENV["GIT_WORK_TREE"]
GIT_DIR = "#{GIT_WORK_TREE}/.git"

filenames = `env GIT_DIR=#{GIT_WORK_TREE}/.git git ls-files`.lines(chomp: true)
number_of_files_to_run_log_for = ARGV.shift.to_i

print "#{filenames.size} files to run log for\n"
print "running log for #{number_of_files_to_run_log_for} files\n"

filenames.take(number_of_files_to_run_log_for).each do |filename|
  print "comparing logs for #{filename}\n"

  absolute_filename = "#{GIT_WORK_TREE}/#{filename}"

  gix_logged_lines = `env GIT_DIR=#{GIT_DIR} gix log #{filename}`.lines(chomp: true)
  git_logged_lines = `env GIT_DIR=#{GIT_DIR} git log --oneline #{absolute_filename}`.lines(chomp: true)

  if gix_logged_lines.size != git_logged_lines.size
    print "logs have different number of lines\n"

    next
  end

  gix_logged_lines.zip(git_logged_lines).each do |(gix_logged_line, git_logged_line)|
    match = gix_logged_line.match(/([0-9a-f]+) (.*)/)

    if match.nil?
      print "`#{git_logged_line}` does not look like a `gix log` line\n"

      next
    end

    gix_hash = match[1]

    match = git_logged_line.match(/([0-9a-f]+) (.*)/)

    if match.nil?
      print "`#{git_logged_line}` does not look like a `git log --oneline` line\n"

      next
    end

    git_hash = match[1]

    if not git_hash.start_with?(gix_hash) and not gix_hash.start_with?(git_hash)
      print "log entries don't match\n"
      print "gix logged #{gix_logged_line} while git logged #{git_logged_line}\n\n"
    end
  end
end