title: Laravel 5 validate csv file error on valid file type
body: <p>I am trying to validate an uploaded csv file with</p>
  
  <pre><code>$validator = Validator::make(
          [
              'file'      =&gt; $file,
              'extension' =&gt; strtolower($file-&gt;getMimeType()),
          ],
          [
              'file'      =&gt; 'required|in:csv',
          ]
      );
  </code></pre>
  
  <p>The validator fails on giving a valid csv file with message <code>The file must be a file of type: csv.</code></p>
  
  <p>The validator passes if i remove <code>in:csv</code>.</p>
  
  <p>Am i doing something wrong?</p>
  
  <p>PS - <code>$file</code> is available and of standard upload file type <code>object(Symfony\Component\HttpFoundation\File\UploadedFile)</code></p>