class ActionController::TestRequest

def assign_parameters(routes, controller_path, action, parameters, generated_path, query_string_keys)
  non_path_parameters = {}
  path_parameters = {}
  parameters.each do |key, value|
    if query_string_keys.include?(key)
      non_path_parameters[key] = value
    else
      if value.is_a?(Array)
        value = value.map(&:to_param)
      else
        value = value.to_param
      end
      path_parameters[key.to_sym] = value
    end
  end
  if get?
    if query_string.blank?
      self.query_string = non_path_parameters.to_query
    end
  else
    if ENCODER.should_multipart?(non_path_parameters)
      self.content_type = ENCODER.content_type
      data = ENCODER.build_multipart non_path_parameters
    else
      fetch_header("CONTENT_TYPE") do |k|
        set_header k, "application/x-www-form-urlencoded"
      end
      case content_mime_type.to_sym
      when nil
        raise "Unknown Content-Type: #{content_type}"
      when :json
        data = ActiveSupport::JSON.encode(non_path_parameters)
      when :xml
        data = non_path_parameters.to_xml
      when :url_encoded_form
        data = non_path_parameters.to_query
      else
        @custom_param_parsers[content_mime_type.symbol] = ->(_) { non_path_parameters }
        data = non_path_parameters.to_query
      end
    end
    data_stream = StringIO.new(data)
    set_header "CONTENT_LENGTH", data_stream.length.to_s
    set_header "rack.input", data_stream
  end
  fetch_header("PATH_INFO") do |k|
    set_header k, generated_path
  end
  path_parameters[:controller] = controller_path
  path_parameters[:action] = action
  self.path_parameters = path_parameters
end