Get changelogs for all gems included in a Rails project

changelog_diff

#!/usr/bin/env ruby

class GemDetails
  attr_accessor :name, :version, :changelog_file


  def initialize(name, version)
    @name, @version = name, version
  end
  def self.from_str(str)
    match = str.match(/(\S+) \((.*)\)/)
    result = self.new(match[1], Gem::Version.new(match[2]))
    result.changelog_file = changelog_for_gem(result.name)
    puts "process gem #{result.name}"
    result
  end
end

def changelog_for_gem(gem)
  changelogs = `bundle exec gem contents #{gem}`.lines.grep(/history|changelog/i)
  if changelogs.empty?
    puts "No changelog found for gem #{gem}"

    return nil
  end
  changelogs.first.chomp
end

def bundler_gems
  gem_list = `bundle list`.lines.drop(1).map do |line|
    line.gsub(/\s*\* /, '')
  end

  gem_list.map { |gem_str| GemDetails.from_str(gem_str) }
end

def bundler_update
  system("bundle update")
end

def bundler_install
  system("bundle install")
end


def updated_gems(initial_gems, new_gems)
  result = []
  initial_gems.each do |gem|
    updated_gem = new_gems.find { |new_gem| gem.name == new_gem.name && gem.version < new_gem.version }
    result << [gem, updated_gem] if updated_gem
  end
  result
end


def changelog_diff
  initial_gems = bundler_gems
  puts "Updating bundle"
  system('bundle update')
  new_gems = bundler_gems
  File.open('bundler_gem_diff.txt', 'w') do |f|
    updated_gems(initial_gems, new_gems).each do |gem_pair|
      f.puts "###### #{gem_pair[0].name} #{gem_pair[0].version} -> #{gem_pair[1].version} ######"
      if gem_pair[0].changelog_file && gem_pair[1].changelog_file
        puts "diff #{gem_pair[0].changelog_file} #{gem_pair[1].changelog_file}"
        f.puts `diff #{gem_pair[0].changelog_file} #{gem_pair[1].changelog_file}`
      else
        f.puts "Missing changelogs"
      end
    end
  end
  system('git checkout Gemfile.lock')
  system('bundle install')
  nil
end

changelog_diff

from http://stackoverflow.com/questions/9470329/get-changelogs-for-all-gems-included-in-a-rails-project?answertab=active#tab-top

Credit to: David Miani http://stackoverflow.com/users/66131/david-miani