How to get rid of an ActiveRecord warning "already initialized constant"

I need to get a proxy class for a specific AR validation

I reuse a piece of code (from Globalize), where it's set as a
constant :

module Globalize
  module Model
    module ActiveRecord
      class << self
        def create_proxy_class(klass)
          Object.const_set "#{klass.name}Translation", Class.new
(::ActiveRecord::Base){..}
..
end

so in my validation module, I can write :
translation_class = Globalize::Model::ActiveRecord.create_proxy_class
(self.class)
no problem when executing it...

but in my model unit tests, I execute it many times, and I get the
warning...
warning: already initialized constant EnumerationTranslation (when
my model class is Enumeration of course)

can I delete this constant in my test setup ? how ?

thanks fyh

erwin