Unexpected `Pundit::AuthorizationNotPerformedError` Has Me Stumped

sessions_controller_spec.rb

# This file adds the beginnings of a spec for the `#new` action to what previously exists in
# https://github.com/jdickey/new_poc/blob/8f2cd52/spec/controllers/sessions_controller_spec.rb

require 'spec_helper'

shared_examples 'invalid login credentials' do |invalid_field_sym|
  user = FactoryGirl.create :user_datum
  if invalid_field_sym == :name
    name = 'An Invalid User Name'
    password = user.password
    description_str = 'the named user does not exist'
  elsif invalid_field_sym == :password
    name = user.name
    password = 'Bogus Password'
    description_str = 'the password is incorrect'
  end

  describe description_str do
    before :each do
      @starting_id = UserData.first.id
      session[:user_id] = @starting_id
      post :create, name: name, password: password
    end

    it 'redirects to the "Sign In" page again' do
      expect(response).to redirect_to new_session_path
    end

    it 'does not change the session data item for the user ID' do
      expect(session[:user_id]).to be @starting_id
    end

    it 'sets the "Invalid user name or password" flash alert message' do
      expect(flash[:alert]).to eq 'Invalid user name or password'
    end
  end # describe description_str

  user.delete
end # shared_examples 'invalid login credentials'

# SessionsController: responsible for logging users in and out.
describe SessionsController do

  describe :routing.to_s, type: :routing do
    it { expect(get '/sessions/new').to route_to 'sessions#new' }
    it { expect(post '/sessions').to route_to 'sessions#create' }
    it { expect(get '/sessions').to_not be_routable }
    it { expect(get '/sessions/1').to_not be_routable }
    it { expect(get '/sessions/edit').to_not be_routable }
    it { expect(put '/sessions/1').to_not be_routable }
    it { expect(delete '/sessions/1').to route_to 'sessions#destroy', id: '1' }
  end

  describe :helpers.to_s do
    it { expect(new_session_path).to eq '/sessions/new' }
    it { expect(sessions_path).to eq '/sessions' }
    it { expect(session_path(1)).to eq '/sessions/1' }
  end

  describe "GET 'new'" do

    # context 'for a Registered User' do
    #   before :each do
    #     @user = FactoryGirl.create :user_datum
    #     session[:user_id] = @user.id
    #     get :new
    #   end
    #
    #   after :each do
    #     session[:user_id] = nil
    #     @user.destroy
    #   end
    #
    #   it 'returns http success' do
    #     expect(response).to be_success
    #   end
    #
    #   it 'assigns a new PostData instance to :post' do
    #     post = assigns[:post]
    #     expect(post).to be_a PostData
    #     expect(post).to be_a_new_record
    #   end
    #
    #   it 'renders the :new template' do
    #     expect(response).to render_template :new
    #   end
    # end # context 'for a Registered User'

    context 'for the Guest User' do
      before :each do
        session[:user_id] = nil
        get :new
      end

      it 'redirects to the landing page' do
        binding.pry
        expect(response).to be_redirection
        expect(response).to redirect_to root_path
      end
    end # context 'for the Guest User'
  end # describe "GET 'new'"

  describe "POST 'create'" do

    describe 'with valid params' do
      let(:user) { FactoryGirl.create :user_datum }

      before :each do
        session[:user_id] = UserData.first.id
        post :create, name: user.name, password: user.password
      end

      it 'redirects to the root URL' do
        expect(response).to redirect_to root_url
      end

      it 'saves the user ID number in the session data' do
        expect(session[:user_id]).to eq user.id
      end

      it 'sets the logged-in flash message' do
        expect(flash[:success]).to eq 'Logged in!'
      end
    end # describe 'with valid params'

    describe 'with parameters that are invalid because' do

      it_behaves_like 'invalid login credentials', :name

      it_behaves_like 'invalid login credentials', :password
    end # describe 'with parameters that are invalid because'
  end # describe "POST 'create'"

  describe "DELETE 'destroy'" do

    before :each do
      @guest_user_id = UserData.first.id
      @user = FactoryGirl.create :user_datum
      session[:user_id] = @guest_user_id
      post :create, name: @user.name, password: @user.password
      expect(session[:user_id]).to be @user.id
      delete :destroy, id: @user.id
    end

    it 'sets the session data item for the user ID to the Guest User' do
      expect(session[:user_id]).to be @guest_user_id
    end

    it 'redirects to the root URL' do
      expect(response).to redirect_to root_url
    end

    it 'sets the "Logged out!" flash message' do
      expect(flash[:success]).to eq 'Logged out!'
    end
  end # describe "DELETE 'destroy'"
end # describe SessionsController

Unexpected Pundit AuthorizationNotPerformedError Has Me Stumped.md

The Tools

1. Pundit Authorisation; experimenting with this pull request linked to from the official Pundit README;
2. ActiveInteraction domain service objects ("DSOs");
3. RSpec 2.99.1

The Project

The project repo is on Github; what's under scrutiny here is on the pundit-1 branch.

I've followed the Pundit tutorial and gotten authorisation working using "traditional" chubby controllers; see

• the PostsController#new action and its spec;
• the Pundit ApplicationPolicy class; and
• the PostDataPolicy governing authorisation for the Rails model instances of Posts.

All well and good so far. And then we come to the SessionController, whose #new and #destroy actions respectively govern logging in and out..

The current code and spec Work Just Fine using traditional-ish controller logic (see how #new calls private methods that use Pundit to authorise the active (current) user using a SessionDataPolicy.

Then I try to encapsulate that logic within an ActiveInteraction DSO (see the commented-out code in SessionsController#new), and all hell breaks loose.

More specifically, the version of the SessionsController spec below raises a Pundit::AuthorizationNotPerformedError at the point where the spec calls the #new method.

Whiskey. Tango. FOX?!?!?

Has anybody been able to get similar code working without Pundit living directly inside the controller code, ideally using @billychan's pull request (a better alternate will be gratefully entertained)?

This has me completely flummoxed.

Discussion transpired on a breadcrumb commit; see this comment and following.