fix comment bumping

app/models/comment.rb

@@ -84,10 +84,10 @@ class Comment < ActiveRecord::Base
   end
 
   def update_last_commented_at
-    if Comment.where("post_id = ?", post_id).count <= Danbooru.config.comment_threshold && !do_not_bump_post
-      execute_sql("UPDATE posts SET last_commented_at = ? WHERE id = ?", created_at, post_id)
-    elsif Comment.where("post_id = ?", post_id).empty?
+    if Comment.where("post_id = ?", post_id).empty?
       execute_sql("UPDATE posts SET last_commented_at = null WHERE id = ?", post_id)
+    elsif Comment.where("post_id = ?", post_id).count <= Danbooru.config.comment_threshold && !do_not_bump_post
+      execute_sql("UPDATE posts SET last_commented_at = ? WHERE id = ?", created_at, post_id)
     end
   end
   

test/unit/comment_test.rb

@@ -32,6 +32,19 @@ class CommentTest < ActiveSupport::TestCase
         Danbooru.config.stubs(:member_comment_limit).returns(100)
         Danbooru.config.stubs(:member_comment_time_threshold).returns(1.week.from_now)
       end
+      
+      context "that is then deleted" do
+        setup do
+          @post = FactoryGirl.create(:post)
+          @comment = FactoryGirl.create(:comment, :post_id => @post.id)
+          @comment.destroy
+          @post.reload
+        end
+        
+        should "nullify the last_commented_at field" do
+          assert_nil(@post.last_commented_at)
+        end
+      end
 
       should "be created" do
         comment = FactoryGirl.build(:comment)