How to test whether right template is rendered (RSpec Rails)?

Im trying to grasp some concepts of TDD and in my RoR app I have /about view which belongs to static_pages#about. It has route defined in routes.rb get 'about' => 'static_pages#about'. Everything works so far in browser but I want to test it by RSpec as well. Given

RSpec.describe "about.html.erb", type: :view do
  it "renders about view" do
    render :template => "about"
    expect(response).to render_template('/about')
  end
end

raises an error

Missing template /about with {:locale=>[:en], :formats=>[:html, :text, :js, :css, :ics, :csv, :vcf, :png, :......

Thanks!

Solution

This spec makes very little sense - the whole idea of a view spec is that you render the view under test and then write expectations (assertions in TDD-speak) about its content. View specs are sometimes useful for testing complex views but are not what you need in this case.

If you want to test that the controller renders the correct template you would do it in a controller spec instead.

require 'rails_helper'
RSpec.describe StaticPagesController, type: :controller do
  describe "GET /about" do
    it "renders the correct template" do
      get :about
      expect(response).to render_template "static_pages/about"
    end
  end
end

Although this kind of spec usually has little value - you're just testing the default behavior of rails and this can be covered by a feature spec which adds more value:

require 'rails_helper'
RSpec.feature "About page" do
  before do
    visit root_path
  end

  scenario "as a vistior I should be able to visit the about page" do
    click_link "About"
    expect(page).to have_content "About AcmeCorp"
  end
end

Note that here we have left the world of TDD an stepped into what is called Behavior Driven Development (BDD). Which is more concerned with the behavior of software and less with the nitty gritty details of how it gets the job done.