add grouped parameter to SubmissionApiController#index

If an assignment is marked to be graded as a group,
speedgrader will group the assignments accordingly, but
in the API, submissions were being returned individually
rather than being grouped. This adds a check for a 'grouped'
param in the SubmissionApiController#index action so that
a single assignment/submission object is returned
per student group.

fixes CNVS-23203

Test Plan:
1. Have a course with a few students enrolled
2. Create user groups and put at least two students
in one group.
3. Create an assignment set to be graded as a group
4. Have a student from one of the groups submit
to the assignment on behalf of the group.
5. With a teacher or admin token, ping the
Submissions list API with params grouped = true
Verify just a single assignment object is returned

Change-Id: I3465b469533d6cff6b3b7c679d8868ceef3dee17
Reviewed-on: https://gerrit.instructure.com/65312
Reviewed-by: Spencer Olson <solson@instructure.com>
Tested-by: Jenkins
Product-Review: Spencer Olson <solson@instructure.com>
QA-Review: Jason Carter <jcarter@instructure.com>

app/controllers/submissions_api_controller.rb

@@ -155,6 +155,9 @@ class SubmissionsApiController < ApplicationController
   # @argument include[] [String, "submission_history"|"submission_comments"|"rubric_assessment"|"assignment"|"visibility"|"course"|"user"]
   #   Associations to include with the group.
   #
+  # @argument grouped [Boolean]
+  #   If this argument is true, the response will be grouped by student groups.
+  #
   # @response_field assignment_id The unique identifier for the assignment.
   # @response_field user_id The id of the user who submitted the assignment.
   # @response_field grader_id The id of the user who graded the assignment.
@@ -177,6 +180,12 @@ class SubmissionsApiController < ApplicationController
       submissions = @assignment.submissions.where(:user_id => visible_student_ids)
       includes = Array.wrap(params[:include])
 
+      # this provides one assignment object(and submission object within), per user group
+      if value_to_boolean(params[:grouped])
+        user_groups_ids = @assignment.representatives(@current_user).map(&:id)
+        submissions = Submission.where(user_id: user_groups_ids, assignment_id: @assignment.id)
+      end
+
       if includes.include?("visibility") && @context.feature_enabled?(:differentiated_assignments)
         json = bulk_process_submissions_for_visibility(submissions, includes)
       else

spec/apis/v1/submissions_api_spec.rb

@@ -3318,4 +3318,57 @@ describe 'Submissions API', type: :request do
       end
     end
   end
+  describe '#index' do
+    context 'grouped_submissions' do
+      let(:test_course) { course() }
+      let(:teacher)   { user(active_all: true) }
+      let(:student1)  { user(active_all: true) }
+      let(:student2)  { user(active_all: true) }
+      let(:group) do
+        group_category = test_course.group_categories.create(name: 'Engineering')
+        test_course.groups.create(name: 'Group1', group_category: group_category)
+      end
+      let(:assignment) do
+        test_course.assignments.create!(
+          title: 'group assignment',
+          grading_type: 'points',
+          points_possible: 10,
+          submission_types: 'online_text_entry',
+          group_category: group.group_category
+        )
+      end
+
+      let!(:enroll_teacher_and_students) do
+        test_course.enroll_teacher(teacher).accept!
+        test_course.enroll_student(student1, enrollment_state: 'active')
+        test_course.enroll_student(student2, enrollment_state: 'active')
+      end
+      let!(:add_students_to_group) do
+        group.add_user(student1)
+        group.add_user(student2)
+      end
+      let!(:submit_homework) { assignment.submit_homework(student1) }
+
+      let(:path) { "/api/v1/courses/#{test_course.id}/assignments/#{assignment.id}/submissions" }
+      let(:params) do
+        {
+          controller: 'submissions_api', action: 'index',
+          format: 'json', course_id: test_course.id.to_s,
+          assignment_id: assignment.id.to_s
+        }
+      end
+
+      it 'should return two assignment and submission objects for a user group' do
+        params[:grouped] = false
+        json = api_call_as_user(teacher, :get, path, params)
+        expect(json.size).to eq 2
+      end
+
+      it 'should return a single assignment and submission object per user group' do
+        params[:grouped] = true
+        json = api_call_as_user(teacher, :get, path, params)
+        expect(json.size).to eq 1
+      end
+    end
+  end
 end