class RSpec::Rails::Matchers::HaveEnqueuedMail

def base_message
  [mailer_class_name, @method_name].compact.join('.').tap do |msg|
    msg << " #{expected_count_message}"
    msg << " with #{@mail_args}," if @mail_args.any?
    msg << " on queue #{@queue}," if @queue
    msg << " at #{@at.inspect}," if @at
    msg << " but enqueued #{@matching_jobs.size}"
  end
end