application_controller_spec.rb

require 'rails_helper'

class ApplicationController < ActionController::Base
  rescue_from ActiveRecord::RecordNotFound, with: :not_found
  rescue_from Pundit::NotAuthorizedError, with: :permission_denied
  rescue_from ActionController::UnknownFormat, with: :unknown_format

  private

  def permission_denied
    flash[:danger] = I18n.t 'pundit.permission_denied'
    redirect_after_rescue
  end

  def unknown_format
    flash[:danger] = I18n.t 'errors.unknown_format'
    redirect_after_rescue
  end

  def not_found
    flash[:danger] = I18n.t 'errors.error_404'
    redirect_after_rescue
  end

  def redirect_after_rescue
    self.response_body = nil
    redirect_to(request.referrer || user_signed_in? ? authenticated_root_path : unauthenticated_root_path)
  end

end

test.rb

RSpec.describe "rescues" do
  controller(ApplicationController) do
    def error_not_found
      raise ActiveRecord::RecordNotFound
    end
    
    def error_not_authorized
      raise Pundit::NotAuthorizedError
    end
    
    def error_unknown_format
      raise ActionController::UnknownFormat
    end
  end

  describe 'handling ActiveRecord::RecordNotFound exceptions' do
    it 'redirects to the root path' do
      get :error_not_found
      expect(response).to redirect_to('/')
      expect(flash[:danger]).to eql 'We kunnen de pagina die je zoekt niet vinden'
    end

    it 'shows the appropriate flash message' do
      get :error_not_found
      expect(flash[:danger]).to eql 'We kunnen de pagina die je zoekt niet vinden'
    end
  end

  describe 'handling Pundit::NotAuthorizedError exceptions' do
    it 'redirects to the root path' do
      get :error_not_authorized
      expect(response).to redirect_to('/')
    end

    it 'shows the appropriate flash message' do
      get :error_not_authorized
      expect(flash[:danger]).to eql 'Je hebt geen toegang tot deze actie'
    end
  end

  describe 'handling ActionController::UnknownFormat exceptions' do
    it 'redirects to the root path' do
      get :error_unknown_format
      expect(response).to redirect_to('/')
    end

    it 'shows the appropriate flash message' do
      get :error_unknown_format
      expect(flash[:danger]).to eql 'We kunnen de pagina die je zoekt niet vinden'
    end
  end
end