Rspec: ActionMailer::Base.deliveries is always empty

This is an integration test using Capybara and Selenium. Therefore, you have to wait for the application to actually send the mail before checking that it has sent it.

Note - this solves the problem but is generally bad practice

Add a sleep 1 to tell rspec to wait after triggering the send mail event. It then resumes by checking the ActionMailer::Base.deliveries array and passed.

As mentioned, this is generally bad practice because it slows down tests.

Better way

Integration test shouldn't test the mail is sent at all. Tests should be divided up into clear responsibilities for the class being tested. Therefore, we'd structure the tests differently so that we only test for the mail being sent in another class (a controller or resource test). We could also use expectations to check that the call to the mail method was actually made though it's possible that we'd still get timing issues.

You should never use sleep or those time consuming methods on the specs, i't will only slow down your specs!

Try using an expectation on your mailer, at the beginning of your test add something like

mail = mock(mail)
mail.should_receive(:deliver)
YourMailer.should_receive(:your_method).once.and_return(mail)

that way you don't have to wait and you are actually testing what you have to test (that the code creates and delivers the mail) and not the mailer code (you only call deliver on a mail object, the actual delivery is a job of the ActionMailer tests and you have nothing to do with it on your application, you should just trust that calling those method works)