Because there is no Preview feature or Test Drive mode for Calendar Events, the best way to know exactly how the confirmation page will display to a user is to register for the event on the front end website. If the event type is a ticketed one, then that would involve making a live transaction on a real credit card, as the test credit card number would not work

If you would like to submit a product enhancement request for the Preview feature and/or Test Drive mode for Calendar Events please comment within the Idea Portal.