title: how do add a project to source control within an existing solution
body: <p>I've recently noticed that my ..LibraryTests project is not under source control:</p>
  
  <p><a href="https://i.stack.imgur.com/SpNo9.png" rel="noreferrer"><img src="https://i.stack.imgur.com/SpNo9.png" alt="enter image description here"></a></p>
  
  <p>When I try to do a checkin (by right clicking on the solution and pressing <strong>check in</strong>) it says that there are <strong>No Pending Changes</strong>. It's not seeing changes to the LibraryTests project because it is not under source control.</p>
  
  <p>From my perspective:</p>
  
  <ol>
  <li>The first project is under source control</li>
  <li>The second project is not under source control</li>
  <li>The solution itself does not seem to be under source control. </li>
  </ol>
  
  <p><strong>How do I get the entire solution including the Tests project checked in?</strong></p>