Add #exp_points to CourseUser model

app/models/course_user.rb

@@ -2,7 +2,13 @@ class CourseUser < ActiveRecord::Base
   belongs_to :user, inverse_of: :course_users
   belongs_to :course, inverse_of: :course_users
   has_many :experience_points_records, class_name: Course::ExperiencePointsRecord.name,
-                                       inverse_of: :course_user, dependent: :destroy
+                                       inverse_of: :course_user, dependent: :destroy do
+    def experience_points
+      sum(:points_awarded)
+    end
+  end
 
   enum role: { student: 0, teaching_assistant: 1, manager: 2, owner: 3 }
+
+  delegate :experience_points, to: :experience_points_records
 end

spec/factories/course_experience_points_records.rb

@@ -3,7 +3,7 @@
     creator
     updater
     course_user
-    points_awarded 100
+    points_awarded { rand(1..20) * 100 }
     reason 'EXP for some event'
   end
 end

spec/models/course_user_spec.rb

@@ -16,4 +16,19 @@
     it { is_expected.to be_student }
     it { is_expected.not_to be_phantom }
   end
+
+  let!(:instance) { create :instance }
+  with_tenant(:instance) do
+    describe '#exp_points' do
+      let!(:exp_record_1) { create(:course_experience_points_record) }
+      let!(:exp_record_2) do
+        create(:course_experience_points_record, course_user: exp_record_1.course_user)
+      end
+      subject { exp_record_1.course_user }
+      it 'sums all associated experience points records' do
+        points_awarded = exp_record_1.points_awarded + exp_record_2.points_awarded
+        expect(subject.experience_points).to eq(points_awarded)
+      end
+    end
+  end
 end