title: FsCheck.xUnit: testing types from another assembly
body: <p>I'm trying to make my first test with FsCheck and xUnit. I have the following setup:</p>
  
  <ul>
  <li><p>An F# class library with a single file</p>
  
  <pre><code>namespace Lib
  type ABC = A | B | C
  </code></pre></li>
  <li><p>A project called Tests with a reference to FsCheck.xUnit NuGet package with a single file:</p>
  
  <pre><code>module LibTests    
  open FsCheck.Xunit
  open Lib    
  [&lt;Property&gt;]
  let ``ABC is always A`` v =
    v = A
  </code></pre></li>
  </ul>
  
  <p>When I run the project (with VS or console runner), I get the following error:</p>
  
  <pre><code>System.Exception : The type Lib.ABC is not handled automatically by FsCheck. 
  Consider using another type or writing and registering a generator for it
  </code></pre>
  
  <p>If I move my type to the Tests assembly, everything works fine (test fails). How do I tests external types?</p>