module MiniTestSpecRails::Init::ActionMailerBehavior

def self.included(klass)
  klass.class_eval do
    register_spec_type(self) { |desc| Class === desc && desc < ActionMailer::Base }
    register_spec_type(/Mailer( ?Test)?\z/i, self)
    register_spec_type(self) { |desc| Class === desc && desc < self }
    register_rails_test_case self
    before { setup_minitest_spec_rails_mailer_class }
  end
end

def setup_minitest_spec_rails_mailer_class
  describing_class.tests described_class
end