controller.rb

class Router::SectionsController < ApplicationController
  def index
    @sections = Router::Section.all()
  end
  def show
    @section = Router::Section.includes(steps: :component_groups)
                              .order("router_steps.position ASC")
                              .find(params[:id])
  end
  def edit
    @section = Router::Section.includes(steps: :component_groups)
                              .order("router_steps.position ASC")
                              .find(params[:id])
    authorize(@section)
    @section.steps.build
  end
  def update
    @section = Router::Section.includes(steps: :component_groups)
                              .order("router_steps.position ASC")
                              .find(params[:id])
    authorize(@section)
    @section.update(params_for_section)
    if @section.save then
      flash[:success] = "Updated"
      redirect_to @section
    else
      flash.now[:danger] = "Could not update"
      render :edit
    end
  end
private
  def params_for_section
    params.require(:router_section).permit(steps_attributes: [:description, :preface, :postface])
  end
end

section.rb

require "test_helper"

class Router::SectionsControllerTest < ActionDispatch::IntegrationTest
  include Devise::Test::IntegrationHelpers
  def test_index
    get router_sections_path
    assert_response :success
  end
  
  def test_show
    @section = router_sections(:sample)
    get router_section_path(@section)
    assert_response :success
  end
  
  def test_edit_no_login
    @section = router_sections(:sample)
    get edit_router_section_path(@section)
    assert_redirected_to root_path
  end

  def test_can_edit_if_admin
    @section = router_sections(:sample)
    login = login(:sample)
    sign_in(login)
    User.any_instance.stubs(:has_role?).returns( lambda { |role| [Roles::ProductionAdmin].include?(role)} )
    get edit_router_section_path(@section)
    assert_response :success
  end

  def test_update_no_login
    @section = router_sections(:sample)
    new_description = "New description!"
    patch router_section_path(@section), router_section: { description: new_description}
    assert_redirected_to root_path
  end
  def test_update_if_login
    @section = router_sections(:sample)
    new_description = "New description!"
    login = login(:sample)
    sign_in(login)
    User.any_instance.stubs(:has_role?).returns( lambda { |role| [Roles::ProductionAdmin].include?(role)} )
    patch router_section_path(@section), router_section: { description: new_description}
    assert_redirected_to @section
  end
  def test_update_nested_attributes
    skip "Later :("
  end
end