title: Proper use of submodules in .NET solutions
body: <p>I have a library I wrote with a structure like this:</p>
  
  <pre><code>SolutionA\
  --Source\
    --Core\
    --Tests\
  --Tools\
    --TestFramework\
    --MockTool\
  SolutionA.sln
  </code></pre>
  
  <p>I want to include this as a submodule for <code>SolutionB</code>.  If I use this entire structure as a submodule, it would get a bunch of stuff that <code>SolutionB</code> doesn't care about; it doesn't care about <code>SolutionA.sln</code>; it doesn't care about <code>Tests\</code>; it doesn't care about <code>Tools\</code>.  Really, <code>SolutionB</code> only cares about <code>Core\</code>.</p>
  
  <p>It looks like I need a separate repository for <code>Core\</code>.  So is it usual practice to have two repositories for .NET solutions whose source is used by other solutions?  One for only the (non-test) code itself (plus needed libraries), and one for the test tools and solution file?</p>