Collection Singular Ids Bug

active_record_bug.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"
  gem "rails", github: "rails/rails"
  gem "arel", github: "rails/arel"
  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 do |t|
  end

  create_table :taggings do |t|
    t.integer :tag_id
    t.integer :post_id
  end

  create_table :tags do |t|
  end
end

class Post < ActiveRecord::Base
  # works with primary_key: "id" or without specifying primary_key
  has_many :taggings, primary_key: :id
  has_many :tags, through: :taggings
end

class Tagging < ActiveRecord::Base
  # works with primary_key: "id" or without specifying primary_key
  belongs_to :tag, primary_key: :id
  belongs_to :post
end

class Tag < ActiveRecord::Base
end

class BugTest < Minitest::Test
  def test_collection_singular_ids_eq
    tagging = Tagging.create!
    post = Post.new(tagging_ids: [tagging.id.to_s])

    assert post.valid?
  end

  def test_collection_singular_ids_eq_with_through_reflection
    tag = Tag.create!
    post = Post.new(tag_ids: [tag.id.to_s])

    assert post.valid?
  end
end