Rails – How do you test ActionMailer sent a specific email in tests

As of rails 3 ActionMailer::Base.deliveries is an array of Mail::Message’s. From the mail documentation:

#  mail['from'] = 'mikel@test.lindsaar.net'
#  mail[:to]    = 'you@test.lindsaar.net'
#  mail.subject 'This is a test email'
#  mail.body    = 'This is a body'
# 
#  mail.to_s #=> "From: mikel@test.lindsaar.net\r\nTo: you@...

From that it should be easy to test your mail’s in an integration

mail = ActionMailer::Base.deliveries.last

assert_equal 'mikel@test.lindsaar.net', mail['from'].to_s

assert_equal 'you@test.lindsaar.net', mail['to'].to_s