monkey patch for fabrication gem that allows Fabricate.unique (for mongoid only at the moment). just require this file within config/environments/test.rb and it should work

fabrication_ext.rb

class Fabricate
  class << self
    def unique(name, overrides={}, &block)
      schematic = Fabrication::Fabricator.schematics[name]
      raise Fabrication::UnfabricatableError, "No fabricator found for '#{name}'" unless schematic

      # pull out the fabricator_id
      fabricator_id = overrides[:fabricator_id] || schematic.attribute(:fabricator_id) || name

      # set the overriden fabricator_id
      overrides[:fabricator_id] = fabricator_id

      # see if there's already a match with that fabricator_id
      existing = schematic.klass.where(:fabricator_id => fabricator_id.to_s).first
      if existing
        attributes = Fabrication::Fabricator.generate(name, {
          :save => false, :attributes => true
        }, overrides, &block)
        existing.update_attributes!(attributes)
        existing
      else
        Fabrication::Fabricator.generate(name, {
          :save => true
        }, overrides, &block)
      end
    end
  end
end

# mongoid helpers adds fabricator_id field and a class level fabricated? helper
module Fabrication
  module Mongoid
    module Helpers
      extend ActiveSupport::Concern
      included do
        # field gets included for any model defined by fabricator
        field :fabricator_id, :type => String
      end

      module ClassMethods
        def fabricated?(id)
          where(:fabricator_id => id.to_s).count > 0
        end
      end
    end
  end
end

# includes helpers within the default Mongoid::Document
module Mongoid
  module Document
    include Fabrication::Mongoid::Helpers
  end
end