public void ToStringTest()
 {
     var text = "Hello";
     Action<TextWriter> action = tw => tw.Write(text);
     var helper = new HelperResult(action);
     Assert.Equal(text, helper.ToString());
 }
        /// <summary>
        /// Initialize system placeholders (for map path to template styles, etc.)
        /// </summary>
        /// <param name="tpl"></param>
        /// <returns></returns>
        public static string InitializeSystemPlaceholders(HelperResult body, string templateVirtualPathPattern, string template, string templateName)
        {
            // Replace with body
            template = template.Replace(_phBody, body.ToString());

            // Remove comments
            template = RemoveComments(template);

            // If template exists
            if( !string.IsNullOrEmpty( templateName ) )
            {
                // Initialize template path placeholders
                template = InitTemplatePathPlaceholders(templateVirtualPathPattern, template, templateName);
            }

            return template;
        }