Extract Contributor concern as abstract class

During documentation of the pair programming feature, we noticed that the Contributor should be an abstract class, which is parent for the User and the ProgrammingGroup. With this commit, we perform these changes.

app/models/concerns/contributor.rb

@@ -1,9 +0,0 @@
-# frozen_string_literal: true
-
-module Contributor
-  extend ActiveSupport::Concern
-
-  included do
-    has_many :submissions, as: :contributor
-  end
-end

app/models/concerns/contributor_creation.rb

@@ -2,7 +2,6 @@
 
 module ContributorCreation
   extend ActiveSupport::Concern
-  include Contributor
 
   ALLOWED_CONTRIBUTOR_TYPES = [InternalUser, ExternalUser, ProgrammingGroup].map(&:to_s).freeze
 

app/models/contributor.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+class Contributor < ApplicationRecord
+  self.abstract_class = true
+
+  has_many :anomaly_notifications, as: :contributor, dependent: :destroy
+  has_many :user_exercise_interventions, as: :contributor
+  has_many :runners, as: :contributor, dependent: :destroy
+
+  has_many :submissions, as: :contributor
+
+  def learner?
+    raise NotImplementedError
+  end
+
+  def teacher?
+    raise NotImplementedError
+  end
+
+  def admin?
+    raise NotImplementedError
+  end
+
+  def internal_user?
+    is_a?(InternalUser)
+  end
+
+  def external_user?
+    is_a?(ExternalUser)
+  end
+
+  def programming_group?
+    is_a?(ProgrammingGroup)
+  end
+
+  def to_s
+    displayname
+  end
+
+  def to_page_context
+    {
+      id:,
+      type: self.class.name,
+      consumer: try(:consumer)&.name, # Only a user is associated with a consumer.
+      displayname:,
+    }
+  end
+end

app/models/programming_group.rb

@@ -1,19 +1,14 @@
 # frozen_string_literal: true
 
-class ProgrammingGroup < ApplicationRecord
+class ProgrammingGroup < Contributor
-  include Contributor
-
-  has_many :anomaly_notifications, as: :contributor, dependent: :destroy
   has_many :programming_group_memberships, dependent: :destroy
   has_many :external_users, through: :programming_group_memberships, source_type: 'ExternalUser', source: :user
   has_many :internal_users, through: :programming_group_memberships, source_type: 'InternalUser', source: :user
-  has_many :testruns, through: :submissions
+  has_many :testruns, through: :submissions # Only a single user starts testruns, but the group has access to them through their submissions.
-  has_many :runners, as: :contributor, dependent: :destroy
+  has_many :events, dependent: :destroy # Only a single user creates events, but the group might be attributed to them optionally.
-  has_many :events, dependent: :destroy
   has_many :events_synchronized_editor, class_name: 'Event::SynchronizedEditor', dependent: :destroy
   has_many :pair_programming_exercise_feedbacks, dependent: :destroy
   has_many :pair_programming_waiting_users, dependent: :destroy
-  has_many :user_exercise_interventions, as: :contributor
   belongs_to :exercise
 
   validate :min_group_size
@@ -21,14 +16,6 @@ class ProgrammingGroup < ApplicationRecord
   validate :no_erroneous_users
   accepts_nested_attributes_for :programming_group_memberships
 
-  def external_user?
-    false
-  end
-
-  def internal_user?
-    false
-  end
-
   def learner?
     true
   end
@@ -45,10 +32,6 @@ class ProgrammingGroup < ApplicationRecord
     Exercise
   end
 
-  def programming_group?
-    true
-  end
-
   def add(user)
     # Accessing the `users` method here will preload all users, which is otherwise done during validation.
     internal_users << user if user.internal_user? && users.exclude?(user)
@@ -56,23 +39,10 @@ class ProgrammingGroup < ApplicationRecord
     user
   end
 
-  def to_s
-    displayname
-  end
-
   def displayname
     "Programming Group #{id}"
   end
 
-  def to_page_context
-    {
-      id:,
-      type: self.class.name,
-      consumer: nil, # A programming group is not associated with a consumer.
-      displayname:,
-    }
-  end
-
   def programming_partner_ids
     users.map(&:id_with_type)
   end

app/models/user.rb

@@ -1,12 +1,11 @@
 # frozen_string_literal: true
 
-class User < ApplicationRecord
+class User < Contributor
   self.abstract_class = true
 
   attr_reader :current_study_group_id
 
   belongs_to :consumer
-  has_many :anomaly_notifications, as: :contributor, dependent: :destroy
   has_many :authentication_token, dependent: :destroy
   has_many :comments, as: :user
   has_many :study_group_memberships, as: :user
@@ -15,15 +14,12 @@ class User < ApplicationRecord
   has_many :programming_groups, through: :programming_group_memberships, as: :user
   has_many :exercises, as: :user
   has_many :file_types, as: :user
-  has_many :submissions, as: :contributor
   has_many :participations, through: :submissions, source: :exercise, as: :user
   has_many :user_proxy_exercise_exercises, as: :user
-  has_many :user_exercise_interventions, as: :contributor
   has_many :testruns, as: :user
   has_many :interventions, through: :user_exercise_interventions
   has_many :remote_evaluation_mappings, as: :user
   has_many :request_for_comments, as: :user
-  has_many :runners, as: :contributor
   has_many :events
   has_many :events_synchronized_editor, class_name: 'Event::SynchronizedEditor'
   has_many :pair_programming_exercise_feedbacks
@@ -31,8 +27,6 @@ class User < ApplicationRecord
   has_one :codeharbor_link, dependent: :destroy
   accepts_nested_attributes_for :user_proxy_exercise_exercises
 
-  scope :with_submissions, -> { where('id IN (SELECT user_id FROM submissions)') }
-
   scope :in_study_group_of, lambda {|user|
                               unless user.admin?
                                 joins(:study_group_memberships)
@@ -46,18 +40,6 @@ class User < ApplicationRecord
 
   validates :platform_admin, inclusion: [true, false]
 
-  def internal_user?
-    is_a?(InternalUser)
-  end
-
-  def external_user?
-    is_a?(ExternalUser)
-  end
-
-  def programming_group?
-    false
-  end
-
   def learner?
     return true if current_study_group_id.nil?
 
@@ -86,19 +68,6 @@ class User < ApplicationRecord
     study_group_memberships.where(study_group: current_study_group_id).limit(1)
   end
 
-  def to_s
-    displayname
-  end
-
-  def to_page_context
-    {
-      id:,
-      type: self.class.name,
-      consumer: consumer.name,
-      displayname:,
-    }
-  end
-
   def self.find_by_id_with_type(id_with_type)
     if id_with_type[0].casecmp('e').zero?
       ExternalUser.find(id_with_type[1..])

db/seeds.rb

@@ -28,7 +28,7 @@ end
 
 # delete all present records
 Rails.application.eager_load!
-(ApplicationRecord.descendants - [ActiveRecord::SchemaMigration, User]).each(&:delete_all)
+(ApplicationRecord.descendants - [ActiveRecord::SchemaMigration, Contributor, User]).each(&:delete_all)
 
 # delete file uploads
 FileUtils.rm_rf(Rails.public_path.join('uploads'))