Get rid of 500 on mobile comment creation

app/controllers/comments_controller.rb

@@ -28,7 +28,7 @@ class CommentsController < ApplicationController
         respond_to do |format|
           format.js{ render(:create, :status => 201)}
           format.html{ render :nothing => true, :status => 201 }
-          format.mobile{ redirect_to @comment.post }
+          format.mobile{ redirect_to post_url(@comment.post) }
         end
       else
         render :nothing => true, :status => 422

spec/controllers/comments_controller_spec.rb

@@ -29,6 +29,10 @@ describe CommentsController do
         response.code.should == '201'
         response.body.should match comment_hash[:text]
       end
+      it 'responds to format mobile' do
+        post :create, comment_hash.merge(:format => 'mobile')
+        response.should be_redirect
+      end
     end
 
     context "on a post from a contact" do