ruby
require 'spec_helper'

module Test_2779
  class Invitation
    include Mongoid::Document
    include Mongoid::Timestamps

    belongs_to :user
    before_destroy :destroy_user

    def destroy_user
      self.user.destroy if self.user
    end
  end

  class User
    include Mongoid::Document
    include Mongoid::Timestamps

    has_many :invitations
  end
end

describe Mongoid do
  it "2779" do
    invitation = Test_2779::Invitation.create!
    user = Test_2779::User.create!
    user.invitations << invitation
    invitation.destroy
  end
end

     Failure/Error: invitation.destroy
     RuntimeError:
       can't modify frozen Hash
     # ./lib/mongoid/attributes.rb:139:in `[]='
     # ./lib/mongoid/attributes.rb:139:in `block in write_attribute'
     # ./lib/mongoid/threaded/lifecycle.rb:26:in `_assigning'
     # ./lib/mongoid/attributes.rb:130:in `write_attribute'
     # ./lib/mongoid/persistence.rb:123:in `touch'
     # ./lib/mongoid/relations/proxy.rb:143:in `method_missing'
     # (eval):4:in `block in touch_user_after_create_or_destroy'
     # ./lib/mongoid/relations/accessors.rb:175:in `without_autobuild'
     # (eval):2:in `touch_user_after_create_or_destroy'
     # ./lib/mongoid/callbacks.rb:128:in `run_callbacks'
     # ./lib/mongoid/persistence.rb:34:in `destroy'
     # ./spec/dblock/2779_spec.rb:29:in `block (2 levels) in <top (required)>'