Controller test for nested resources

can't go over the problem with CREATING INDEX ROUTE TEST for nested attribute. I've been trying all my ideas but nothing works

I have Service model and ServiceRoute model.

ServiceRoute belongs_to Service

and

Service has_many ServiceRoutes.

Here is my controller:

class ServiceRoutesController < ApplicationController

before_action :set_service_route, only: [:show, :update, :destroy]
before_action :set_service, only: :create


def create
  @service_route = @service.service_routes.build(service_route_params)

  if @service_route.save
    render json: @service_route, status: :created, location: @service_route
  else
    render json: @service_route.errors, status: :unprocessable_entity
  end
end


private

  def set_service_route
    @service_route = ServiceRoute.find(params[:id])
  end

  def set_service
   @service = Service.find(params[:service_id])
  end

  def service_route_params
    params.require(:service_route).permit(:routes_list, :service_id)
  end
end

I create ServiceRoute with build method

My routes.rb file:

resources :services do
  resources :service_routes
end

Test "should create service route" has an error:

ActionController::UrlGenerationError: No route matches {:action=>"index", :controller=>"service_routes"} missing required keys: [:service_id]

test "should create service_route" do
 assert_difference('ServiceRoute.count') do
  post service_service_routes_url, params: { service_route: {routes_list: 
  @service_route.routes_list, service_id: @service_route.service_id } }, 
 as: :json
end

How should I refactor this test to match the route: /services/:service_id/service_routes