Open all of your updated gem's changes at once

updated_gems.rb

#!/usr/bin/env ruby

VERSION_REGEX = /\((\d.+)\)/
require 'net/http'
require 'json'
lines = `git diff Gemfile.lock`.split("\n")
# Line is a diffed line
lines.select!{ |line| ['+ ', '- '].include?(line.strip[0..1])}
# Line has a version
lines.select!{ |line| line.match(VERSION_REGEX) }
added, removed = {}, {}
lines.each do |line|
  name, version = line[1..-1].strip.split
  version = version.match(VERSION_REGEX).captures.first
  if line[0] == "+"
    added[name] = version
  else
    removed[name] = version
  end
end

added.each do |name, version|
  json = JSON.parse Net::HTTP.get_response('rubygems.org', "/api/v1/gems/#{name}.json").body
  uri = nil
  %w{ source_code_uri homepage_uri }.each do |key|
    next if uri
    uri = json[key] && json[key].match(/github\.com/) && json[key]
  end
  if uri
    uri = "#{uri}/compare/v#{removed[name]}...v#{version}" if removed.has_key?(name)
    `open #{uri}`
  else
    puts "Can't find github URL for gem: #{name}"
  end
end