class RSpec::Mocks::AnyInstance::Recorder

def observe!(method_name)
  if RSpec::Mocks.configuration.verify_partial_doubles?
    raise MockExpectationError unless @klass.method_defined?(method_name)
  end
  stop_observing!(method_name) if already_observing?(method_name)
  @observed_methods << method_name
  backup_method!(method_name)
  @klass.__send__(:define_method, method_name) do |*args, &blk|
    klass = ::RSpec::Mocks.method_handle_for(self, method_name).owner
    ::RSpec::Mocks.any_instance_recorder_for(klass).playback!(self, method_name)
    self.__send__(method_name, *args, &blk)
  end
end