ship_date column to the orders table, and send a notification when this value is updated by the
Hint: Active Record provides dirty methods to enable you to check to see if a field has changed.
Update the application to send an e-mail to the system administrator, namely yourself, when there is an application failure such as the one we handled in Section 10.2.
Hint: Create a new notifier specifically for errors.
Add integration tests for both of the above.
Hint: ActionMailer::Base.deliveries contains the emails that would have been sent.