require 'mongoid'

Mongoid.configure do |config|
  config.clients.default = {
    hosts: ['localhost:27017'],
    database: 'my_db',
  }

  config.log_level = :warn
end

$logger = []

class Root
  include Mongoid::Document
  embeds_many :embedded_once, cascade_callbacks: true
  after_save :trace

  def trace
    $logger << "A"
  end
end

class EmbeddedOnce
  include Mongoid::Document
  embeds_many :embedded_twice, cascade_callbacks: true
  embedded_in :root
  after_save :trace

  def trace
    $logger << "B"
  end
end

class EmbeddedTwice
  include Mongoid::Document
  embedded_in :embedded_once
  after_save :trace

  def trace
    $logger << "C"
  end
end

require 'minitest/autorun'

class EmbedHookTest < MiniTest::Unit::TestCase
  def setup
    @root= Root.new(
      embedded_once: [
        EmbeddedOnce.new(
          embedded_twice: [EmbeddedTwice.new]
        )
      ]
    )
  end

  def test_hooks
    @root.save
    assert_equal(["A", "B", "C"], $logger)
    # Actual is C, C, B, A
  end
end