Great episode, Chris. I like how you said you don't really need to test CSS styling but instead focus on testing the higher level functionality of your mailers. That way, a developer doesn't go down a rabbit hole writing too fine grained tests.

Also, the last point about ActionMailer::Base.deliveries makes me wonder what the difference is between that and assert_emails.

Cool, thanks. I've been using mailcatcher, which is great for developing but you have to reload! in the console to get changes in the templates to show up. Previews looks much better.