title: Adding custom tag helpers
body: <p>I've been trying to add a custom tag helper, but when I try to add the assembly as a reference in the _ViewImports.cshtml it doesn't recognise it.</p>
  
  <p>I'm doing this (_ViewImports.cshtml):</p>
  
  <pre><code>@using ProjectName.Web.Main
  @addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers
  @addTagHelper *, TagHelpers
  </code></pre>
  
  <p>and also I've tried:</p>
  
  <pre><code>@addTagHelper *, ProjectName.Web.Main.TagHelpers
  </code></pre>
  
  <p>my tag helper is the following:</p>
  
  <pre><code>using Microsoft.AspNetCore.Razor.TagHelpers;
  namespace ProjectName.Web.Main.TagHelpers
  {
      [HtmlTargetElement(Attributes="class")]
      public class CssClassTagHelper : TagHelper
      {
          public override void Process(TagHelperContext context, TagHelperOutput output)
          {
              output.Attributes.Add(new TagHelperAttribute("class","testing"));
  
          }
      }
  }
  </code></pre>
  
  <p>but when I run the app, I get the following exception:</p>
  
  <blockquote>
    <p>Cannot resolve TagHelper containing assembly 'TagHelpers'. Error:
    Could not load file or assembly 'TagHelpers, Culture=neutral,
    PublicKeyToken=null' or one of its dependencies. The system cannot
    find the file specified. @addTagHelper *, TagHelpers</p>
  </blockquote>
  
  <p>I already have googled it but I'm getting mixed answers between the different dotnetcore releases, so far I haven't found any solution.</p>
  
  <p>I'm using RC2.</p>
  
  <p>any ideas, suggestions?</p>