assert_did_not_send_email.rb

class Test::Unit::TestCase
  
  def assert_did_not_send_email
    if block_given?
      msg = "One or more sent emails matched your criteria.\n"
      emails = ::ActionMailer::Base.deliveries
      matching_emails = emails.select {|email| yield email }
      assert matching_emails.empty?, msg
    else
      msg = "Sent #{::ActionMailer::Base.deliveries.size} emails.\n"
      ::ActionMailer::Base.deliveries.each { |m| msg << "  '#{m.subject}' sent to #{m.to.to_sentence}\n" }
      assert ::ActionMailer::Base.deliveries.empty?, msg
    end
  end
  
end