Remove PairProgramming23Study and instead use LTI parameter

app/controllers/concerns/lti.rb

@@ -226,6 +226,7 @@ module Lti
     @lti_parameters.save!
 
     session[:external_user_id] = current_user.id
+    session[:pair_programming] = parameters[:custom_pair_programming] || false
   rescue ActiveRecord::RecordNotUnique, ActiveRecord::RecordInvalid
     retry
   end

app/controllers/exercises_controller.rb

@@ -305,6 +305,7 @@ class ExercisesController < ApplicationController
       # we are acting on behalf of a programming group
       if current_user.admin?
         session.delete(:pg_id)
+        session.delete(:pair_programming)
         @current_contributor = current_user
       else
         return redirect_back(
@@ -316,9 +317,9 @@ class ExercisesController < ApplicationController
       # we are just acting on behalf of a single user who has already worked on this exercise as part of a programming group **in the context of the current study group**
       session[:pg_id] = pg.id
       @current_contributor = pg
-    elsif session[:pg_id].blank? && PairProgramming23Study.participate_in_pp?(current_user, @exercise) && PairProgramming23Study::FORCED_EXERCISE_IDS.include?(@exercise.id)
+    elsif session[:pg_id].blank? && session[:pair_programming] == 'mandatory'
       return redirect_back(fallback_location: new_exercise_programming_group_path(@exercise))
-    elsif session[:pg_id].blank? && PairProgramming23Study.participate?(current_user, @exercise) && current_user.submissions.where(study_group_id: current_user.current_study_group_id, exercise: @exercise).none?
+    elsif session[:pg_id].blank? && session[:pair_programming] == 'optional' && current_user.submissions.where(study_group_id: current_user.current_study_group_id, exercise: @exercise).none?
       Event.find_or_create_by(category: 'pp_work_alone', user: current_user, exercise: @exercise, data: nil, file_id: nil)
       current_user.pair_programming_waiting_users&.find_by(exercise: @exercise)&.update(status: :worked_alone)
     end

app/controllers/sessions_controller.rb

@@ -19,12 +19,15 @@ class SessionsController < ApplicationController
   def create_through_lti
     return redirect_to_survey if params[:custom_survey_id]
 
-    session.delete(:pg_id) # Remove any previous pg_id from the session
+    # Remove any previous pg_id and pair_programming option from the session
+    session.delete(:pg_id)
+    session.delete(:pair_programming)
+
     store_lti_session_data(params)
     store_nonce(params[:oauth_nonce])
     if params[:custom_redirect_target]
       redirect_to(URI.parse(params[:custom_redirect_target].to_s).path)
-    elsif PairProgramming23Study.participate?(current_user, @exercise)
+    elsif params[:custom_pair_programming]
       redirect_to(new_exercise_programming_group_path(@exercise))
     else
       redirect_to(implement_exercise_path(@exercise),
@@ -57,6 +60,7 @@ class SessionsController < ApplicationController
       session.delete(:study_group_id)
       session.delete(:embed_options)
       session.delete(:pg_id)
+      session.delete(:pair_programming)
 
       # In case we have another session as an internal user, we set the study group for this one
       internal_user = find_or_login_current_user
@@ -98,7 +102,6 @@ class SessionsController < ApplicationController
         # add a user pseudo ID if applicable
         qp[:xi_pseudo_id] = Digest::SHA256.hexdigest(current_user.external_id)
         qp[:co_study_group_id] = current_user.current_study_group_id
-        qp[:co_pair_programming23_study] = PairProgramming23Study.participate_in_pp?(current_user, @exercise).to_s
         qp[:co_rfcs] = current_user.request_for_comments.includes(:submission).where(submission: {study_group_id: current_user.current_study_group_id}).size.to_s
         qp[:co_comments] = current_user.comments.includes(:submission).where(submission: {study_group_id: current_user.current_study_group_id}).size.to_s
       end

app/views/programming_groups/new.html.slim

@@ -5,7 +5,7 @@ h1.d-inline-block = t('programming_groups.new.create_programming_pair')
 #matching data-exercise-id=@exercise.id.to_s
   .row
     .col-12.mt-2.mb-4
-      - if PairProgramming23Study.participate_in_pp?(current_user, @exercise) && PairProgramming23Study::FORCED_EXERCISE_IDS.include?(@exercise.id)
+      - if session[:pair_programming] == 'mandatory'
         p = t('programming_groups.new.info_forced_work_together', exercise_title: @exercise.title)
       - else
         p = t('programming_groups.new.info_work_together', exercise_title: @exercise.title)
@@ -32,7 +32,7 @@ h1.d-inline-block = t('programming_groups.new.create_programming_pair')
     .col-12.d-none.d-md-block
       = render('form')
 
-  - unless PairProgramming23Study.participate_in_pp?(current_user, @exercise) && PairProgramming23Study::FORCED_EXERCISE_IDS.include?(@exercise.id)
+  - unless session[:pair_programming] == 'mandatory'
     .row
       .col-12
         h5 = t('programming_groups.new.work_alone')

lib/pair_programming23_study.rb

@@ -1,46 +0,0 @@
-# frozen_string_literal: true
-
-class PairProgramming23Study
-  ENABLE = ENV.fetch('PAIR_PROGRAMMING_23_STUDY', nil) == 'true'
-  STUDY_GROUP_IDS = [368, 451].freeze
-  # All easy tasks of the first week to be solved by the participants on their own
-  EXCLUDED_EXERCISE_IDS = [636, 647, 648, 649, 637, 638, 623, 639, 650, 625, 624, 651, 653, 654, 655, 664, 656].freeze
-  # The participants are forced to work in pairs on these tasks
-  FORCED_EXERCISE_IDS = [723].freeze
-
-  def self.participate?(user, exercise)
-    return false if Rails.env.test?
-
-    ENABLE || participate_in_pp?(user, exercise)
-  end
-
-  def self.participate_in_pp?(user, exercise)
-    return false unless experiment_course?(user.current_study_group_id)
-    return false if EXCLUDED_EXERCISE_IDS.include?(exercise.id)
-    return true if user.external_user? && fixed_enrolled_users.include?([user.consumer_id.to_s, user.external_id])
-
-    user_group = user.id % 3 # => 0, 1, 2
-    case user_group
-      when 0, 1
-        true
-      else # 2
-        false
-    end
-  end
-
-  def self.experiment_course?(study_group_id)
-    STUDY_GROUP_IDS.include? study_group_id
-  end
-
-  def self.csv
-    @csv ||= CSV.read(Rails.root.join('config/pair_programming23_study.csv'), headers: true)
-  rescue Errno::ENOENT
-    []
-  end
-
-  def self.fixed_enrolled_users
-    @fixed_enrolled_users ||= csv.map do |row|
-      [row['consumer_id'], row['external_id']]
-    end
-  end
-end

spec/concerns/lti_spec.rb

@@ -163,6 +163,7 @@ RSpec.describe Lti do
       controller.instance_variable_set(:@current_user, create(:external_user))
       controller.instance_variable_set(:@exercise, create(:fibonacci))
       expect(controller.session).to receive(:[]=).with(:external_user_id, anything)
+      expect(controller.session).to receive(:[]=).with(:pair_programming, anything)
       controller.send(:store_lti_session_data, parameters)
     end
 

spec/controllers/sessions_controller_spec.rb

@@ -194,6 +194,7 @@ RSpec.describe SessionsController do
         expect(controller.session).to receive(:delete).with(:study_group_id)
         expect(controller.session).to receive(:delete).with(:embed_options)
         expect(controller.session).to receive(:delete).with(:pg_id)
+        expect(controller.session).to receive(:delete).with(:pair_programming)
         delete :destroy
       end