Reproduce call save in `getter` method bug in rails 4.2

gistfile1.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', '4.2.0'
  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|
    t.string :title
  end
end

class Post < ActiveRecord::Base
  def title
    if self[:title].blank?
      update_attribute :title, "test"
    end
    self[:title]
  end
end


class BugTest < Minitest::Test
  def test_association_stuff
    post = Post.create!(title: "aa")
    post.update_attribute :title, nil

    assert_equal "test", post.title
  end
end