Edited at

RailsのActiveRecordなどを単体で動かしてpry-byebugでデバッグする

Railsのソースコード読んでても黒魔術がいっぱいで、どうやって動いてるのかよく分からんです。

rails newで素のサンプルアプリケーションを作って、 pry-byebug などのデバッカを差し込んでもよいんですけど、railsのバグ報告に使われてるissueテンプレート使うと1ファイルで書けるし、rubyはdockerで実行しちゃえばクリーンな環境でできそう。

元ネタは以下です。

https://github.com/rails/rails/blob/646dd8c51fc438bf935d4192ba0479e439c1ec54/guides/bug_report_templates/active_record_gem.rb

pry-byebugの設定を追加で差し込んでおきます。


test.rb

# 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", "6.0.0.rc2"
gem "sqlite3"
gem 'pry-byebug'
end

require "active_record"
require "minitest/autorun"
require "logger"
require 'pry'

if defined?(PryByebug)
Pry.commands.alias_command 'c', 'continue'
Pry.commands.alias_command 's', 'step'
Pry.commands.alias_command 'n', 'next'
Pry.commands.alias_command 'f', 'finish'
end

binding.pry

# 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


$ docker run -it --rm -v $(pwd):/tmp/work ruby:2.6.3 /bin/bash

root@27dd893231b5:/# ruby /tmp/work/test.rb

From: /tmp/work/test.rb @ line 31 :

26: end
27:
28: binding.pry
29:
30: # This connection will do for database-independent bug reports.
=> 31: ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
32: ActiveRecord::Base.logger = Logger.new(STDOUT)
33:
34: ActiveRecord::Schema.define do
35: create_table :posts, force: true do |t|
36: end

あとはご自由に。