I'm playing with rspec and factory girl but I'm stuck with a validation error for duplicate device entries while testing even if it should create different apps and devices for every test

app_models_device.rb

class Device < ActiveRecord::Base
  attr_accessible :app_id, :app_version, :locale, :push_token, :uid, :alias

  belongs_to :app

  validates_presence_of :app
  
  validates :push_token,
    :presence => true, :uniqueness => {:scope => :app_id, :message => 'already registered'}

  validates_presence_of :locale
  
  
  
end

spec_factories_app.rb

FactoryGirl.define do

  factory :app do
    environment 'production'
    sequence(:name){|n| "Test#{n}Application"}
    os 'iOS'
    version '1.0'
    sequence(:bundle_identifier){|n| "com.getting_angry.Test#{n}Application"}
    certificate_expire_at nil
    app_administrator '[email protected]'

    #created 10 devices
    after(:create) do |app, evaluator|
      FactoryGirl.create_list(:device, 8, app: app)
      FactoryGirl.build_list(:en_US_device, 2, app: app)
    end
    
    factory :app_with_notifications do
      ignore do
        notifications_count 5 #default nr
      end

      after(:create) do |app, evaluator|
        FactoryGirl.create_list(:notification, evaluator.notifications_count, app: app)
      end

    end
    
    factory :app_with_broadcast_notifications do

      ignore do
        notifications_count 10 #default nr
      end

      after(:create) do |app, evaluator|
        FactoryGirl.create_list(:broadcast_notification, evaluator.notifications_count, app: app)
      end

    end
    
  end
end

spec_factories_device.rb

FactoryGirl.define do
  
  factory :device do |d|
      d.app_version '1.0'
      d.locale 'it_IT'
      d.sequence(:push_token){|p| 'raad0saadw0wdi0ae9a#{p}'}
      d.uid 'test_user'

      d.association :app, factory: :app

      factory :en_US_device do |e|
        e.locale 'en_US'
      end

  end

end

spec_models_app.rb

require "spec_helper"

describe App do

  it "should limit notifications sent" do
    a = FactoryGirl.create(:app_with_notifications,notifications_count: 80)
    a.notifications.length.should == 80
    a.should_receive(:send_notifications).exactly(2).times
    a.check_notifications(true)
  end
  
  it "should generate 'broadcast' notifications" do
    a = FactoryGirl.create(:app_with_broadcast_notifications, notifications_count: 1)
    a.notifications.length.should == 1
    data = a.explode_notification(a.notifications.first)
    data.length.should == a.devices.count
  end
  
end

Couple of other ideas:

Future-proof your app and use strong_parameters over attr_accessible:

https://github.com/rails/strong_parameters

Use the FactoryGirl shorthand syntax methods:

# spec/spec_helper.rb
RSpec.configure do |config|
  config.include FactoryGirl::Syntax::Methods
end

app = create(:app_with_notifications, notifications_count: 80)