bookings_controller.rb

class BookingsController < ApplicationController
  def index
    # `order` was added prematurely and in the result may remain untested
    bookings = Booking.order(customer_name: :asc)

    render :index, locals: { bookings: bookings }
  end
end

bookings_controller_spec.rb

RSpec.describe BookingsController do
  describe '#index' do
    it 'renders all bookings' do
      bookings = create_list(:booking, 5)
      allow(controller).to receive(:render).and_call_original

      get :index

      expect(controller).to have_received(:render).
        with(:index, locals: { bookings: match_array(bookings) })
    end
  end
end