Update Grading Period to support parent assignment

flag=discussion_checkpoints
fixes VICE-3829

test plan:
- new spec passes
- whatever else you can think of

Change-Id: Ic5a558b20e1bcf67b44929f915d83bbd321a48ef
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/351785
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Jason Gillett <jason.gillett@instructure.com>
QA-Review: Omar Soto-Fortuño <omar.soto@instructure.com>
Product-Review: Caleb Guanzon <cguanzon@instructure.com>

app/services/checkpoints/submission_aggregator_service.rb

@@ -25,6 +25,7 @@ class Checkpoints::SubmissionAggregatorService < Checkpoints::AggregatorService
     :graded_anonymously,
     :grader_id,
     :grade_matches_current_submission,
+    :grading_period_id,
     :late_policy_status,
     :published_grade,
     :published_score,
@@ -71,6 +72,7 @@ class Checkpoints::SubmissionAggregatorService < Checkpoints::AggregatorService
 
     submission.excused = submissions.any?(&:excused)
     submission.grade = grade(submissions, submission.score)
+    submission.grading_period_id = shared_attribute(submissions, :grading_period_id, nil)
     submission.late_policy_status = calculate_late_policy_status(submissions)
     submission.published_grade = grade(submissions, submission.published_score)
     submission.grade_matches_current_submission = calculate_grade_matches_current_submission(submissions)

spec/services/checkpoints/submission_aggregator_service_spec.rb

@@ -715,6 +715,44 @@ describe Checkpoints::SubmissionAggregatorService do
       end
     end
 
+    describe "grading_period_id" do
+      before :once do
+        gpg = GradingPeriodGroup.create! title: "asdf",
+                                         root_account: @course.root_account
+        @course.enrollment_term.update grading_period_group: gpg
+        @term1 = gpg.grading_periods.create! title: "past grading period",
+                                             start_date: 2.weeks.ago,
+                                             end_date: 1.week.ago
+        @term2 = gpg.grading_periods.create! title: "current grading period",
+                                             start_date: 2.days.ago,
+                                             end_date: 2.days.from_now
+      end
+
+      it "sets the grading_period_id to the grading_period_id shared by both checkpoints" do
+        submission.grading_period_id = nil
+        submission.save!
+
+        # before running the service, make sure checkpoint submissions are still in @term2
+        expect(sub_assignment_submissions.first.grading_period_id).to eq @term2.id
+        expect(sub_assignment_submissions.last.grading_period_id).to eq @term2.id
+
+        success = service_call
+        expect(success).to be true
+        expect(submission.reload.grading_period_id).to eq @term2.id
+      end
+
+      it "sets the grading_period_id to nil when checkpoints are in different grading periods" do
+        Submission.suspend_callbacks(:aggregate_checkpoint_submissions) do
+          sub_assignment_submissions.first.update!(grading_period_id: @term1.id)
+          sub_assignment_submissions.last.update!(grading_period_id: @term2.id)
+        end
+
+        success = service_call
+        expect(success).to be true
+        expect(submission.reload.grading_period_id).to be_nil
+      end
+    end
+
     describe "late_policy_status" do
       it "computes late + late = late" do
         Submission.suspend_callbacks(:aggregate_checkpoint_submissions) do