rubrics getting deleted incorrectly

a rubric should only be deleted once it's not
being used anymore.  It should only be unbookmarked
from a given context when it's not being used in
that context anymore.

fixes #3309

Change-Id: Icb8a79baeb0c0ec2195b7e19b1d9768eadfeb97e
Reviewed-on: https://gerrit.instructure.com/2518
Tested-by: Hudson <hudson@instructure.com>
Reviewed-by: JT Olds <jt@instructure.com>
Reviewed-by: Brian Palmer <brianp@instructure.com>

app/controllers/rubric_associations_controller.rb

@@ -55,7 +55,11 @@ class RubricAssociationsController < ApplicationController
     @rubric = @association.rubric
     if authorized_action(@association, @current_user, :delete)
       @association.destroy
-      if !RubricAssociation.for_purpose('bookmark').find_by_rubric_id(@rubric.id)
+      # If the rubric wasn't created as a general course rubric,
+      # and this was the last place it was being used in the course, 
+      # go ahead and delete the rubric from the course.
+      association_count = RubricAssociation.scoped(:conditions => {:context_id => @context.id, :context_type => @context.class.to_s, :rubric_id => @rubric.id}).for_grading.count
+      if !RubricAssociation.for_purpose('bookmark').find_by_rubric_id(@rubric.id) && association_count == 0
         @rubric.destroy_for(@context)
       end
       render :json => @association.to_json

app/models/rubric.rb

@@ -99,9 +99,14 @@ class Rubric < ActiveRecord::Base
     self.save
   end
   
+  # If any rubric_associations for a given context are marked as
+  # bookmarked, then the rubric will show up in the context's list
+  # of rubrics.  The two main values for the 'purpose' field on
+  # a rubric_association are 'grading' and 'bookmark'.  Confusing,
+  # I know.
   def destroy_for(context)
     RubricAssociation.update_all({:bookmarked => false, :updated_at => Time.now}, {:rubric_id => self.id, :context_id => context.id, :context_type => context.class.to_s})
-    if !self.read_only && self.rubric_associations.for_grading.length < 2
+    if RubricAssociation.scoped(:conditions => {:rubric_id => self.id, :bookmarked => true}).count == 0
       self.destroy
     end
   end

app/models/rubric_association.rb

@@ -130,7 +130,7 @@ class RubricAssociation < ActiveRecord::Base
   end
   
   def update_values
-    self.bookmarked = true if self.purpose == 'bookmark'
+    self.bookmarked = true if self.purpose == 'bookmark' || self.bookmarked.nil?
     self.context_code ||= "#{self.context_type.underscore}_#{self.context_id}" rescue nil
     self.title ||= (self.association.title rescue self.association.name) rescue nil
   end