I have a actionmailer model that send the user a URL to the website for account activation. In my unit tests for the model I want to ensure that the correct URL is being generated. In the test I have the following: assert sent.body.include? new_account_activation_url(:activation_code => user.perishable_token) When I run the test, I get undefined method ''new_account_activation_url''. ''new_account_activation_url'' works fine in the model so I know it is not a routing problem. I assume that I need to include some helper to get this to work but I am not sure what to include. Any ideas? Thanks!