always expose submission.posted_at to the api

fixes GRADE-2416

test plan:
 - specs pass

Change-Id: I56536b659c23542e74e21493c0f099909880ee18
Reviewed-on: https://gerrit.instructure.com/208350
Tested-by: Jenkins
Reviewed-by: Derek Bender <djbender@instructure.com>
Reviewed-by: Jeremy Neander <jneander@instructure.com>
QA-Review: Keith Garner <kgarner@instructure.com>
Product-Review: Keith Garner <kgarner@instructure.com>

lib/api/v1/submission.rb

@@ -119,7 +119,7 @@ module Api::V1::Submission
 
   SUBMISSION_JSON_FIELDS = %w(id user_id url score grade excused attempt submission_type submitted_at body
     assignment_id graded_at grade_matches_current_submission grader_id workflow_state late_policy_status
-    points_deducted grading_period_id cached_due_date extra_attempts).freeze
+    points_deducted grading_period_id cached_due_date extra_attempts posted_at).freeze
   SUBMISSION_JSON_METHODS = %w(late missing seconds_late entered_grade entered_score).freeze
   SUBMISSION_OTHER_FIELDS = %w(attachments discussion_entries).freeze
 
@@ -128,7 +128,6 @@ module Api::V1::Submission
     includes = Array.wrap(params[:include])
 
     json_fields = SUBMISSION_JSON_FIELDS
-    json_fields += ['posted_at'] if context.post_policies_enabled?
     json_methods = SUBMISSION_JSON_METHODS.dup # dup because AR#to_json modifies the :methods param in-place
     other_fields = SUBMISSION_OTHER_FIELDS
 

spec/apis/v1/assignments_api_spec.rb

@@ -4961,6 +4961,7 @@ describe AssignmentsApiController, type: :request do
          "grading_period_id" => @submission.grading_period_id,
          "grade_matches_current_submission" => true,
          "graded_at" => nil,
+         "posted_at" => nil,
          "grader_id" => @teacher.id,
          "id" => @submission.id,
          "score" => 99.0,
@@ -5000,6 +5001,7 @@ describe AssignmentsApiController, type: :request do
          "grading_period_id" => @submission.grading_period_id,
          "grade_matches_current_submission" => true,
          "graded_at" => nil,
+         "posted_at" => nil,
          "grader_id" => @teacher.id,
          "id" => @submission.id,
          "score" => 99.0,

spec/apis/v1/stream_items_api_spec.rb

@@ -402,6 +402,7 @@ describe UsersController, type: :request do
       'excused' => false,
       'grader_id' => @teacher.id,
       'graded_at' => @sub.graded_at.as_json,
+      'posted_at' => @sub.posted_at.as_json,
       'score' => 12.0,
       'entered_score' => 12.0,
       'html_url' => "http://www.example.com/courses/#{@course.id}/assignments/#{@assignment.id}/submissions/#{@user.id}",
@@ -531,6 +532,7 @@ describe UsersController, type: :request do
       'excused' => false,
       'grader_id' => @teacher.id,
       'graded_at' => nil,
+      'posted_at' => nil,
       'score' => nil,
       'entered_score' => nil,
       'html_url' => "http://www.example.com/courses/#{@course.id}/assignments/#{@assignment.id}/submissions/#{@user.id}",

spec/apis/v1/submissions_api_spec.rb

@@ -900,6 +900,7 @@ describe 'Submissions API', type: :request do
         "excused" => sub1.excused,
         "grader_id"=>@teacher.id,
         "graded_at"=>sub1.graded_at.as_json,
+        "posted_at"=>sub1.posted_at.as_json,
         "body"=>"test!",
         "assignment_id" => a1.id,
         "cached_due_date" => nil,
@@ -1081,6 +1082,7 @@ describe 'Submissions API', type: :request do
         "excused" => sub1.excused,
         "grader_id"=>@teacher.id,
         "graded_at"=>sub1.graded_at.as_json,
+        "posted_at"=>sub1.posted_at.as_json,
         "body"=>"test!",
         "assignment_id" => a1.id,
         "submitted_at"=>"1970-01-01T03:00:00Z",
@@ -1122,6 +1124,7 @@ describe 'Submissions API', type: :request do
            "excused" => nil,
            "grader_id"=>nil,
            "graded_at"=>nil,
+           "posted_at"=>nil,
            "body"=>"test!",
            "assignment_id" => a1.id,
            "submitted_at"=>"1970-01-01T01:00:00Z",
@@ -1148,6 +1151,7 @@ describe 'Submissions API', type: :request do
            "excused" => nil,
            "grader_id"=>nil,
            "graded_at"=>nil,
+           "posted_at"=>nil,
            "assignment_id" => a1.id,
            "media_comment" =>
             { "media_type"=>"video",
@@ -1180,6 +1184,7 @@ describe 'Submissions API', type: :request do
            "excused" => false,
            "grader_id"=>@teacher.id,
            "graded_at"=>sub1.graded_at.as_json,
+           "posted_at"=>sub1.posted_at.as_json,
            "assignment_id" => a1.id,
            "media_comment" =>
             { "media_type"=>"video",
@@ -1276,6 +1281,7 @@ describe 'Submissions API', type: :request do
         "grader_id"=>@teacher.id,
         "cached_due_date" => nil,
         "graded_at"=>sub2.graded_at.as_json,
+        "posted_at"=>sub2.posted_at.as_json,
         "assignment_id" => a1.id,
         "body"=>nil,
         "preview_url" => "http://www.example.com/courses/#{@course.id}/assignments/#{a1.id}/submissions/#{student2.id}?preview=1&version=1",
@@ -1290,6 +1296,7 @@ describe 'Submissions API', type: :request do
            "excused" => false,
            "grader_id"=>@teacher.id,
            "graded_at"=>sub2.graded_at.as_json,
+           "posted_at"=>sub2.posted_at.as_json,
            "assignment_id" => a1.id,
            "body"=>nil,
            "submitted_at"=>"1970-01-01T04:00:00Z",

spec/lib/api/v1/submission_spec.rb

@@ -514,8 +514,11 @@ describe Api::V1::Submission do
         expect(json.fetch('posted_at')).to eq posted_at
       end
 
-      it "is not included if the owning course does not have post policies enabled" do
-        expect(json).not_to have_key('posted_at')
+      it "is included if the owning course does not have post policies enabled" do
+        posted_at = Time.zone.now
+        submission.update!(posted_at: posted_at)
+
+        expect(json.fetch('posted_at')).to eq posted_at
       end
     end
   end