bundler/inline

bundler の定義を１ファイル内に記述するためのテクニックが bundler/inline。

Gemfileをいちいち作らなくてもよいので便利。

Bundler: How to use Bundler in a single-file Ruby script

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'json', require: false
  gem 'nap', require: 'rest'
  gem 'cocoapods', '~> 0.34.1'
end

puts 'Gems installed and loaded!'
puts "The nap gem is at version #{REST::VERSION}"

Rails Bug Template

Rails Bug Template においても、bundler/inline が使われている。

rails/active_record_gem.rb at v7.0.0 · rails/rails

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  # Activate the gem you are reporting the issue against.
  gem "activerecord", "~> 6.1.0"
  gem "sqlite3"
end

require "active_record"
require "minitest/autorun"
require "logger"

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :posts, force: true do |t|
  end

  create_table :comments, force: true do |t|
    t.integer :post_id
  end
end

class Post < ActiveRecord::Base
  has_many :comments
end

class Comment < ActiveRecord::Base
  belongs_to :post
end

class BugTest < Minitest::Test
  def test_association_stuff
    post = Post.create!
    post.comments << Comment.create!

    assert_equal 1, post.comments.count
    assert_equal 1, Comment.count
    assert_equal post.id, Comment.first.post.id
  end
end

特定バージョンのgemの動作検証やバグを報告するのに便利なテクニック。