title: How do I pass mocked objects in a mocked container object
body: <p>My method is expecting a FloFilesList which is a class that stores a list of FloFile objects (a class that describes and performs actions on certain types of files)</p>
  
  <p>The method I'm calling returns 1 FloFile based on the value of FloFile.FileName.</p>
  
  <p>I want to use the interface IFloFile to initialize the mock object rather than set FloFile.FileName to be Virtual just because I'm told that Interfaces are the way to go.</p>
  
  <pre><code> var mockFloFileOne = new Mock&lt;IFloFile&gt;();
          mockFloFileOne.SetupGet(f =&gt; f.FileName).Returns("FileName.xml");
  </code></pre>
  
  <p>How can I add the mock FloFile into the mock FloFilesList?
  I tried this.</p>
  
  <pre><code>var mockFloFileList = new Mock&lt;FloFilesList&gt;();
  mockFloFileList.Object.Add(mockFloFileOne.Object);
  </code></pre>
  
  <p>This doesn't work as I get an error "...IFloFile is not assignable to FloFile"</p>
  
  <p>How do I mock FloFilesList ?</p>