preload_test.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", "5.0.2"
  gem "sqlite3"
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|
  end

  create_table :tags, force: true do |t|
    t.datetime :deleted_at
  end

  create_table :post_tags, force: true do |t|
    t.references :post, null: false
    t.references :tag, null: false
  end
end

class PostTag < ActiveRecord::Base
  belongs_to :post
  belongs_to :tag
end

class Post < ActiveRecord::Base
  has_many :post_tags
  has_many :tags, -> { active }, through: :post_tags
end

class Tag < ActiveRecord::Base
  has_many :post_tags
  has_many :posts, through: :post_tags

  scope :active, -> { where(deleted_at: nil) }
end

class BugTest < Minitest::Test
  def test_association_stuff
    post = Post.create!
    tag = Tag.create!
    PostTag.create!(tag: tag, post: post)

    # Passes:

    begin
      Post.all.map{ |post| post.tags }
    rescue ActiveRecord::StatementInvalid => error
      flunk("raised '#{error.inspect}'")
    end

    # Fails:

    begin
      Post.preload(:tags).map{ |post| post.tags }
    rescue ActiveRecord::StatementInvalid => error
      flunk("raised '#{error.inspect}'")
    end
  end
end