gistfile1.rb

# recent github checkout
$:.unshift(File.dirname(__FILE__) + '/lib/mongomapper/lib/')

require 'mongo_mapper'
require 'spec'

MongoMapper.database = 'tmp'

class Party
  include MongoMapper::Document

  many :guests

  def invite(name)
    if guests.any? { |g| g.name == name }
      errors.add(:guests, 'duplicate name') # after this the errors stay empty
    else
      guests << Guest.new(:name => name)
    end
  end
end

class Guest
  include MongoMapper::EmbeddedDocument

  key :name, :required => true
end

context 'Party' do

  before(:each){ Party.collection.remove }

  it 'is boring without guests' do
    party = Party.create

    party.invite('George')
    party.should be_valid
    party.guests.length.should == 1
  end

  it 'leads to confusion if guests are named the same' do
    party = Party.create

    party.invite('George')
    party.invite('Melinda')
    party.invite('George')
    party.guests.length.should == 2 # this is ok
    party.should_not be_valid       # this fails
  end

end