support_slash_mail.rb

# If you're sending html-only mail (Shame on you! 😆) you can use the following so you get support for
# it { should have_sent_email.matching_html_part(/html-only contents/) }

module Mail
  module Matchers
    class HasSentEmailMatcher
      def matching_html_part(html_part_matcher)
        @html_part_matcher = html_part_matcher
        self
      end

      def matches_on_html_part_matcher?(delivery)
        @html_part_matcher.match delivery.html_part.raw_source
      end
    end
  end
end