Capybara custom matcher for image and favicon validation of presence and existing file

capybara_custom_matcher_asset.rb

# frozen_string_literal: true

module Capybara
  module CustomMatchers
    include Capybara::DSL

    class Asset
      def asset_exists?(actual, src)
        js_script = <<JSS
xhr = new XMLHttpRequest();
xhr.open('GET', '#{src}', true);
xhr.send();
JSS
        actual.execute_script(js_script)
        status = actual.evaluate_script('xhr.status') # get js variable value
        status == 200 || status == 302
      end
    end

    class LoadImage < Asset
      def initialize(*args)
        @args = args
        @src = args.first
      end

      def matches?(actual)
        is_present = actual.has_selector?("img[src='#{@src}']")
        is_present && asset_exists?(actual, @src)
      end

      def does_not_match?(actual)
        actual.has_no_selector?("img[src='#{@src}']")
      end

      def failure_message
        "No image loaded with source: '#{@src}'"
      end

      def failure_message_when_negated
        "Image loaded with source: '#{@src}'"
      end

      def description
        "Verify if image with source: '#{@src}' is loaded"
      end
    end

    class LoadFavicon < Asset
      def initialize(*args)
        @args = args
        @rel = args.first
        @href = args.second
      end

      def matches?(actual)
        is_present = actual.has_selector?("link[rel='#{@rel}'][href='#{@href}']", visible: false)
        is_present && asset_exists?(actual, @href)
      end

      def does_not_match?(actual)
        actual.has_no_selector?("link[rel='#{@rel}'][href='#{@href}']", visible: false)
      end

      def failure_message
        "No favicon loaded with rel: '#{@rel}' and href: '#{@href}'"
      end

      def failure_message_when_negated
        "Favicon loaded with rel: '#{@rel}' and href: '#{@href}'"
      end

      def description
        "Verify if favicon with rel: '#{@rel}' and href: '#{@href}' is loaded"
      end
    end

    def load_image(*args)
      LoadImage.new(*args)
    end

    def load_favicon(*args)
      LoadFavicon.new(*args)
    end
  end
end

RSpec.configure do |config|
  config.include Capybara::CustomMatchers
end