Gets html content from View result

GetHtmlFromViewResult.cs

private async Task<string> GetHtml(Controller controller, ViewResult viewResult)
{
    using (var stringWriter = new StringWriter())
    {
        var viewEngineResult = viewResult.ViewEngine.FindView(controller.ControllerContext, 
            viewResult.ViewName, 
            false);

        var viewContext = new ViewContext(
            controller.ControllerContext,
            viewEngineResult.View,
            viewResult.ViewData,
            viewResult.TempData,
            stringWriter, 
            new HtmlHelperOptions());

        await viewEngineResult.View.RenderAsync(viewContext);

        return stringWriter.ToString();
    }
}