Better error message for "I follow the link in the email"

[makmic]

The current implementation of the mentioned step is missing a safeguard if paths is empty, i.e. when no link has been found in the mail. It is quite hard to debug as visit nil will trigger an exception somewhere else.

# Please note that this step will only follow HTTP and HTTPS links.
# Other links (such as mailto: or ftp:// links) are ignored.
When /^I follow the (first|second|third)? ?link in the e?mail$/ do |index_in_words|
  mail = @mail || ActionMailer::Base.deliveries.last
  index = { nil => 0, 'first' => 0, 'second' => 1, 'third' => 2 }[index_in_words]
  url_pattern = %r((?:https?://[^/]+)([^"'\s]+))

  paths = if mail.html_part
    dom = Nokogiri::HTML(mail.html_part.body.to_s)
    (dom / 'a[href]').map { |a| a['href'].match(url_pattern) }.compact.map { |match| match[1] }
  else
    mail_body = MailFinder.email_text_body(mail).to_s
    mail_body.scan(url_pattern).flatten(1)
  end

  visit paths[index]
end.overridable

I'd love to see a better error message in this case