Rakefile

require "bundler/gem_tasks"
require "bundler/gem_helper"
require 'rspec/core/rake_task'
require 'octokit'

Octokit.configure do |c|
  c.login        = `git config --get github.user`.strip
  c.access_token = `git config --get github.token`.strip
end

desc 'Release gem and create a release on GitHub'
task 'create_release' => 'release' do
  t = Bundler::GemHelper.new
  current_version  = "v#{t.gemspec.version.to_s}"
  previous_version = ""
  `git tag`.split(/\n/).each do |tag|
    break if tag == current_version
    previous_version = tag
  end

  log = `git log #{previous_version}..#{current_version} --grep=Merge`

  repo = `git remote -v | grep origin`.match(/([\w-]+\/[\w-]+)\.git/)[1]

  description = []
  log.split(/commit/).each do |lines|
    lines.match(/Merge pull request \#(\d+)/) do |m|
      url = "https://github.com/#{repo}/pull/#{m[1]}"
      title = Octokit.pull_request(repo, m[1]).title
      description << "* [#{title}](#{url})"
    end
  end

  Octokit.create_release(
    repo,
    current_version,
    body: description.join("\n"),
  )
end