test.rb

# Activate the gem you are reporting the issue against.
gem 'activerecord', '4.1.7'
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 do |t|
    t.string :title
  end
end

class Post < ActiveRecord::Base
end

class BugTest < Minitest::Test
  def test_association_stuff
    post = Post.create!(title: "hello!")
    all = nil

    Post.where(title: "other").first_or_initialize { all = Post.all }

    assert_includes all, post
  end
end