gistfile1.rb

class Campaign
  include Mongoid::Document
  field :name
  index :name, :unique => true

  validates_presence_of :name
end


describe Campaign do 
  context "validation" do
    it "should validate uniqueness of name" do
      campaign_a = campaign_b = Campaign.new(:name => 'Testing')
      campaign_a.save
      campaign_b.valid?.should be_true
    end
  end
end