fix pinning of discussions on pages > 1

fixes CNVS-8314

test plan:
  * create over 100 discussions in a course;
  * as a teacher, navigate to the course discussions page;
  * scroll to the bottom of the page and, using the gear
    menu, attempt to pin the bottom-most discussion;
  * verify that it properly pins.

Change-Id: Icc064daf2316d8de37e6b45d6e6bb40320f5c90b
Reviewed-on: https://gerrit.instructure.com/24786
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Braden Anderson <banderson@instructure.com>
Product-Review: Zach Pendleton <zachp@instructure.com>
QA-Review: Zach Pendleton <zachp@instructure.com>

app/coffeescripts/bundles/discussion_topics_index.coffee

@@ -58,7 +58,7 @@ require [
     # Returns nothing.
     fetchDiscussions: ->
       pipeline = new DiscussionTopicsCollection
-      pipeline.fetch(add: true, data: {order_by: 'recent_activity', per_page: 50})
+      pipeline.fetch(data: {order_by: 'recent_activity', per_page: 50})
       pipeline.on('fetch', @_onPipelineLoad)
       pipeline.on('fetched:last', @_onPipelineEnd)
 
@@ -101,8 +101,8 @@ require [
     #
     # Returns nothing.
     _onPipelineLoad: (collection, models) =>
-      @_sortCollection(collection)
-      setTimeout((-> collection.fetch(add: true, page: 'next')), 0) if collection.urls.next
+      @_sortCollection(models)
+      setTimeout((-> collection.fetch(page: 'next')), 0) if collection.urls.next
 
     # Internal: Handle the last page of discussion topic results, propagating
     # the event down to all of the filtered collections.
@@ -135,7 +135,7 @@ require [
     # Returns an object.
     _groupModels: (pipeline) ->
       defaults = { pinned: [], locked: [], open: [] }
-      _.extend(defaults, pipeline.groupBy(@_modelBucket))
+      _.extend(defaults, _.groupBy(pipeline, @_modelBucket))
 
     # Determine the name of the model's proper collection.
     #
@@ -143,8 +143,12 @@ require [
     #
     # Returns a string.
     _modelBucket: (model) ->
-      return 'pinned' if model.get('pinned')
-      return 'locked' if model.get('locked') || model.get('locked_for_user')
+      if model.attributes
+        return 'pinned' if model.get('pinned')
+        return 'locked' if model.get('locked') || model.get('locked_for_user')
+      else
+        return 'pinned' if model.pinned
+        return 'locked' if model.locked || model.locked_for_user
       'open'
 
     # Internal: Move a model from one collection to another.

app/coffeescripts/views/DiscussionTopics/DiscussionView.coffee

@@ -72,19 +72,6 @@ define [
       @model.save(locked: locked, pinned: pinned)
       $(e.target).text(@messages[key])
 
-    # Public: Pin or unpin the model and update it on the server.
-    #
-    # e - Event object.
-    #
-    # Returns nothing.
-    togglePinned: (e) =>
-      e.preventDefault()
-      key = if @model.get('pinned') then 'pin' else 'unpin'
-      pinned = !@model.get('pinned')
-      locked = if pinned then false else @model.get('locked')
-      @model.save(locked: locked, pinned: pinned)
-      $(e.target).text(@messages[key])
-
     # Public: Confirm a request to delete and then complete it if needed.
     #
     # e - Event object.

spec/selenium/discussions_spec.rb

@@ -359,6 +359,22 @@ describe "discussions" do
           ffj('.open.discussion-list li.discussion:visible').length.should == 1
         end
 
+        it "should allow pinning of all pages of topics" do
+          100.times do |n|
+            DiscussionTopic.create!(context: @course, user: @teacher,
+              title: "Discussion Topic #{n+1}")
+          end
+          topic = DiscussionTopic.where(context_id: @course.id).order('id DESC').last
+          topic.should_not be_pinned
+          get(url)
+          wait_for_ajaximations
+          keep_trying_until { fj(".al-trigger") }
+          fj("[data-id=#{topic.id}] .al-trigger").click
+          fj('.icon-pin:visible').click
+          wait_for_ajaximations
+          topic.reload.should be_pinned
+        end
+
         it "should allow locking a pinned topic" do
           topic = @course.discussion_topics.create!(title: 'Test Discussion', user: @user, pinned: true)
           get(url)