Add ProgrammingGroup & ProgrammingGroupMembership

* User can create programming group with other users for exercise
* Submission is shared in a group
* Also adjust specs

app/controllers/programming_groups_controller.rb

@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+class ProgrammingGroupsController < ApplicationController
+  include CommonBehavior
+  include LtiHelper
+
+  before_action :set_exercise_and_authorize
+
+  def new
+    @programming_group = ProgrammingGroup.new(exercise: @exercise)
+    authorize!
+    existing_programming_group = current_user.programming_groups.find_by(exercise: @exercise)
+    if existing_programming_group
+      session[:pg_id] = existing_programming_group.id
+      redirect_to(implement_exercise_path(@exercise),
+        notice: t("sessions.create_through_lti.session_#{lti_outcome_service?(@exercise.id, current_user.id) ? 'with' : 'without'}_outcome", consumer: @consumer))
+    end
+  end
+
+  def create
+    programming_partner_ids = programming_group_params[:programming_partner_ids].split(',').map(&:strip).uniq
+    users = programming_partner_ids.map do |partner_id|
+      User.find_by_id_with_type(partner_id)
+    rescue ActiveRecord::RecordNotFound
+      partner_id
+    end
+    @programming_group = ProgrammingGroup.new(exercise: @exercise, users:)
+    authorize!
+
+    unless programming_partner_ids.include? current_user.id_with_type
+      @programming_group.add(current_user)
+    end
+
+    create_and_respond(object: @programming_group, path: proc { implement_exercise_path(@exercise) }) do
+      session[:pg_id] = @programming_group.id
+      nil
+    end
+  end
+
+  private
+
+  def authorize!
+    authorize(@programming_group || @programming_groups)
+  end
+
+  def programming_group_params
+    params.require(:programming_group).permit(:programming_partner_ids)
+  end
+
+  def set_exercise_and_authorize
+    @exercise = Exercise.find(params[:exercise_id])
+    authorize(@exercise, :implement?)
+  end
+end