class WebMock::Response

def assert_valid_body!
  valid_types = [Proc, IO, Pathname, String, Array]
  return if @body.nil?
  return if valid_types.any? { |c| @body.is_a?(c) }
  if @body.is_a?(Hash)
    raise InvalidBody, "must be one of: #{valid_types}, but you've used a #{@body.class}. " \
      "Please convert it by calling .to_json .to_xml, or otherwise convert it to a string."
  else
    raise InvalidBody, "must be one of: #{valid_types}. '#{@body.class}' given."
  end
end