title: How should Rust unit tests be organised?
body: <p>I have a number of methods in a <code>mod</code>. These methods need to be tested but they're private. I currently have the unit tests inside the same <code>mod</code>, but I'm not sure this is the right way to go about it, as I'm mixing two different things.</p>
  
  <p>Should I put my unit tests in a different file? If so, how do I test private methods?</p>