submission comments controller: allow changing comments

Allows changing the 'comment' attribute on a submission comment via the
update action on the SubmissionCommentsController. In addition, adjusts
the update action so that it returns string IDs when the request
includes a header for canvas string IDs.

refs GRADE-335

Test Plan:
1. Verify specs pass. A thorough test plan will be included in a
   follow-up commit to this one, where it will be possible to test this
   behavior via the UI.

Change-Id: I0b8327e6911daff09e9150601685cfd0e30dab35
Reviewed-on: https://gerrit.instructure.com/129883
Tested-by: Jenkins
Reviewed-by: Jeremy Neander <jneander@instructure.com>
Reviewed-by: Shahbaz Javeed <sjaveed@instructure.com>
QA-Review: Anju Reddy <areddy@instructure.com>
Product-Review: Keith T. Garner <kgarner@instructure.com>

app/controllers/submission_comments_controller.rb

@@ -25,7 +25,7 @@ class SubmissionCommentsController < ApplicationController
       submission_comment.reload unless submission_comment.update(submission_comment_params)
 
       respond_to do |format|
-        format.json { render json: submission_comment }
+        format.json { render json: submission_comment.as_json }
       end
     end
   end
@@ -43,6 +43,6 @@ class SubmissionCommentsController < ApplicationController
   private
 
   def submission_comment_params
-    params.require(:submission_comment).permit(:draft)
+    params.require(:submission_comment).permit(:draft, :comment)
   end
 end

spec/controllers/submission_comments_controller_spec.rb

@@ -49,8 +49,41 @@ describe SubmissionCommentsController do
       user_session(@the_teacher)
     end
 
-    it 'allows updating the status field' do
-      expect { patch 'update', params: @test_params }.to change { SubmissionComment.draft.count }.by(-1)
+    it "allows updating the comment" do
+      updated_comment = "an updated comment!"
+      patch(
+        :update,
+        params: @test_params.merge(submission_comment: { comment: updated_comment })
+      )
+      comment = JSON.parse(response.body).dig("submission_comment", "comment")
+      expect(comment).to eq updated_comment
+    end
+
+    it "sets the edited_at if the comment is updated" do
+      updated_comment = "an updated comment!"
+      patch(
+        :update,
+        params: @test_params.merge(submission_comment: { comment: updated_comment })
+      )
+      edited_at = JSON.parse(response.body).dig("submission_comment", "edited_at")
+      expect(edited_at).to be_present
+    end
+
+    it "returns strings for numeric values when passed the json+canvas-string-ids header" do
+      request.headers["HTTP_ACCEPT"] = "application/json+canvas-string-ids"
+      patch :update, params: @test_params
+      id = JSON.parse(response.body).dig("submission_comment", "id")
+      expect(id).to be_a String
+    end
+
+    it "does not set the edited_at if the comment is not updated" do
+      patch :update, params: @test_params
+      edited_at = JSON.parse(response.body).dig("submission_comment", "edited_at")
+      expect(edited_at).to be_nil
+    end
+
+    it "allows updating the status field" do
+      expect { patch "update", params: @test_params }.to change { SubmissionComment.draft.count }.by(-1)
     end
   end
 end