capybara has_image? matcher

1-has_image.rb

module Capybara
  class Session
    def has_image?(src)
      has_xpath?("//img[contains(@src,\"/images/#{src}\")]")
    end
  end
end

2-use.rb

Then /^the biometrics section should be marked incomplete$/ do
  within "#assessment-menu" do
    page.should have_image "warning_24.png"
  end
end

Cheers for this!