module RSpec::Core::SharedExampleGroup

def share_as(name, &block)
  if Object.const_defined?(name)
    mod = Object.const_get(name)
    raise_name_error unless mod.created_from_caller(caller)
  end
  mod = Module.new do
    @shared_block = block
    @caller_line = caller.last
    def self.created_from_caller(other_caller)
      @caller_line == other_caller.last
    end
    def self.included(kls)
      kls.module_eval(&@shared_block)
    end
  end
  shared_const = Object.const_set(name, mod)
  RSpec.world.shared_example_groups[shared_const] = block
end