hide unread count on group discussions

fixes CNVS-15309

test plan
- create a course level group discussion
- view the course's discussion index page
- ensure that the unread count is not displayed for the group
 discussion

Change-Id: I0605a8c669de42686790d25d2db25261a57bd967
Reviewed-on: https://gerrit.instructure.com/95981
Tested-by: Jenkins
Reviewed-by: Clay Diffrient <cdiffrient@instructure.com>
QA-Review: Deepeeca Soundarrajan <dsoundarrajan@instructure.com>
Product-Review: Joel Hough <joel@instructure.com>

Author: JoelHough

app/coffeescripts/models/DiscussionTopic.coffee

@@ -84,6 +84,7 @@ define [
         reply_count_tooltip: @replyTooltip()
         assignment: json.assignment?.toJSON()
         defaultDates: @defaultDates().toJSON()
+        isRootTopic: @isRootTopic()
       delete json.assignment.rubric if json.assignment
       json
 
@@ -183,6 +184,9 @@ define [
         $toFocus = $('.ig-header-title', $toFocus) if $toFocus.hasClass('discussion-list')
         $toFocus.focus()
 
+    isRootTopic: () ->
+      !@get('root_topic_id') && @get('group_category_id')
+
     groupCategoryId: (id) =>
       return @get( 'group_category_id' ) unless arguments.length > 0
       @set 'group_category_id', id

app/views/jst/DiscussionTopics/discussion.handlebars

@@ -65,6 +65,7 @@
     </div>
 
     <div class="discussion-unread-status">
+      {{#unless isRootTopic}}
       <div class="new-and-total-badge pull-right">
         <span class="new-items"
               title="{{unread_count_tooltip}}"
@@ -86,6 +87,7 @@
           {{reply_count_tooltip}}
         </div>
       </div>
+      {{/unless}}
     </div>
 
     <div class="discussion-actions">

spec/selenium/discussions/discussions_index_page_any_user_spec.rb

@@ -9,6 +9,7 @@
   let(:teacher) { teacher_in_course(course: course, name: 'teacher', active_all: true).user }
   let(:somebody) { student_in_course(course: course, name: 'somebody', active_all: true).user }
   let(:somebody_topic) { course.discussion_topics.create!(user: somebody, title: 'somebody topic title', message: 'somebody topic message') }
+  let(:group_topic) { group_discussion_assignment }
   let(:assignment_group) { course.assignment_groups.create!(name: 'assignment group') }
   let(:entry) { topic.discussion_entries.create!(user: teacher, message: 'teacher entry') }
 
@@ -107,6 +108,12 @@
         expect(f('.total-items').text).to eq '1'
       end
 
+      it "hides unread count for group discussions" do
+        group_topic
+        get url
+        expect(f(".discussion-unread-status").text).to eq ''
+      end
+
       describe 'filtering' do
         before(:each) do
           @graded_unread_topic = topic_for_filtering(read: false, graded: true)