association_testcase.rb

# Run with `ruby association_testcase.rb`
begin
  require "bundler/inline"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end

gemfile(true) do
  source "https://rubygems.org"
  # Activate the gem you are reporting the issue against.
  gem "activerecord", "5.0.0"
  gem "sqlite3"
  gem "pry"
end

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

# Ensure backward compatibility with Minitest 4
Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)

# 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|
        t.string :title
      end

      create_table :comments, force: true do |t|
        t.text :body, null: false
        t.integer :post_id
      end
    end

    class Post < ActiveRecord::Base
      has_many :comments
      validates :title, uniqueness: true
      accepts_nested_attributes_for :comments
    end

    class Comment < ActiveRecord::Base
      belongs_to :post
    end

class BugTest < Minitest::Test
  def test_nested_attributes_rollback_behaviour
    posts = [Post.new(title: "The truth about toothpaste and toothbrushes", comments_attributes: [{ body: "Comment" }])]

    ActiveRecord::Base.transaction do
      posts.each do |p|
        p.save
        # Collecting validation errors here for presentation purposes
      end
      raise ActiveRecord::Rollback
    end

    # Now the comment attributes seem to be gone
    # and this line should not raise
    posts.each { |p| post.save }

    assert_equal 1, posts.first.comments.count
    assert_equal "Comment", Comment.first.body
    assert_equal post.id, Comment.first.post.id
  end
end