module RSpec::Matchers

def self.is_a_matcher?(obj)
  return true  if ::RSpec::Matchers::BuiltIn::BaseMatcher === obj
  return false if obj.respond_to?(:i_respond_to_everything_so_im_not_really_a_matcher)
  return false unless obj.respond_to?(:matches?)
  obj.respond_to?(:failure_message_for_should) || obj.respond_to?(:failure_message)
end