fix post grades placement for lti 2

test plan:
 * install a post grades lti 2 tool
 * the post grades placement should be shown for the tool
 * the tool should be shown on the gradebook page for posting grades

fixes SKYW-106

Change-Id: I25f26c09017d8967799b3692a2aeb15986a4c322
Reviewed-on: https://gerrit.instructure.com/57576
Reviewed-by: Nathan Mills <nathanm@instructure.com>
Tested-by: Jenkins
QA-Review: Steven Shepherd <sshepherd@instructure.com>
Product-Review: Mark Severson <markse@instructure.com>

app/controllers/gradebooks_controller.rb

@@ -211,7 +211,7 @@ class GradebooksController < ApplicationController
       case launch_definition[:definition_type]
       when 'ContextExternalTool'
         url = external_tool_url_for_lti1(launch_definition)
-      when 'MessageHandler'
+      when 'Lti::MessageHandler'
         url = external_tool_url_for_lti2(launch_definition)
       end
       launch_definition[:placements][:post_grades][:canvas_launch_url] = url

app/models/lti/resource_placement.rb

@@ -19,19 +19,21 @@
 module Lti
   class ResourcePlacement < ActiveRecord::Base
 
-    RESOURCE_SELECTION = 'resource_selection'
-    ASSIGNMENT_SELECTION = 'assignment_selection'
-    LINK_SELECTION = 'link_selection'
     ACCOUNT_NAVIGATION = 'account_navigation'
+    ASSIGNMENT_SELECTION = 'assignment_selection'
     COURSE_NAVIGATION = 'course_navigation'
+    LINK_SELECTION = 'link_selection'
+    POST_GRADES = 'post_grades'
+    RESOURCE_SELECTION = 'resource_selection'
 
-    DEFAULT_PLACEMENTS = [ASSIGNMENT_SELECTION, LINK_SELECTION]
+    DEFAULT_PLACEMENTS = [ASSIGNMENT_SELECTION, LINK_SELECTION].freeze
 
     PLACEMENT_LOOKUP = {
       'Canvas.placements.accountNavigation' => ACCOUNT_NAVIGATION,
+      'Canvas.placements.assignmentSelection' => ASSIGNMENT_SELECTION,
       'Canvas.placements.courseNavigation' => COURSE_NAVIGATION,
       'Canvas.placements.linkSelection' => LINK_SELECTION,
-      'Canvas.placements.assignmentSelection' => ASSIGNMENT_SELECTION,
+      'Canvas.placements.postGrades' => POST_GRADES,
     }.freeze
 
     attr_accessible :placement, :message_handler, :resource_handler
@@ -43,4 +45,4 @@ module Lti
     validates_inclusion_of :placement, :in => PLACEMENT_LOOKUP.values
 
   end
-end
+end

app/models/lti/tool_consumer_profile_creator.rb

@@ -14,6 +14,7 @@ module Lti
           Canvas.placements.courseNavigation
           Canvas.placements.assignmentSelection
           Canvas.placements.linkSelection
+          Canvas.placements.postGrades
           User.username
           Person.email.primary
           Person.name.given

lib/lti/app_launch_collator.rb

@@ -90,7 +90,11 @@ module Lti
 
     def self.lti2_placements(message_handler, placements)
       resource_placements = message_handler.placements.pluck(:placement)
-      valid_placements = resource_placements.present? ? resource_placements & placements : ResourcePlacement::DEFAULT_PLACEMENTS
+      if resource_placements.present?
+        valid_placements = resource_placements & placements.map(&:to_s)
+      else
+        valid_placements = ResourcePlacement::DEFAULT_PLACEMENTS
+      end
       valid_placements.each_with_object({}) { |p, hsh| hsh[p.to_sym] = lti2_placement(message_handler) }
     end