wrappertaghelper.cs

public class WrapperTagHelper : TagHelper
    {
        public override void Process(TagHelperContext context, TagHelperOutput output)
        {
            output.TagName = "div";
            output.Attributes.SetAttribute(new TagHelperAttribute("class", "wrapper-tag-helper"));

            string innerContent = renderInnerTagHelper(context);

            string finalContent = $@"<p>Wrapper</p>
{innerContent}";

            output.Content.SetHtmlContent(finalContent);
        }

        /*
         * This methods creates, processes and renders the InnerTagHelper
         */
        private string renderInnerTagHelper(TagHelperContext context)
        {
            InnerTagHelper innerTagHelper = new InnerTagHelper();

            // Create a TagHelperOutput instance
            TagHelperOutput innerOutput = new TagHelperOutput(
                tagName: "",
                attributes: new TagHelperAttributeList(),
                getChildContentAsync: (useCachedResult, encoder) =>
                     Task.Factory.StartNew<TagHelperContent>(
                            () => new DefaultTagHelperContent()
                     )
            );

            // Process the InnerTagHelper instance 
            innerTagHelper.Process(context, innerOutput);

            // Render and return the tag helper attributes and content
            return $"<{innerOutput.TagName} {renderHtmlAttributes(innerOutput)}>{innerOutput.Content.GetContent()}</{innerOutput.TagName}>";
        }
        .
        .
        <code omitted here>
        .
        .
    }
}