title: Can files be nested in VS2017 Solution Explorer for .NET Core (non-ASP.NET Core) projects?
body: <p>In "old school" MSBuild projects - as still used by Windows Forms in VS2017 for example - files could be "nested" via a <code>DependentUpon</code> item in the csproj file.</p>
  
  <p>I used this to group unit tests together in Noda Time, e.g.</p>
  
  <pre><code>&lt;Compile Include="LocalDateTest.PeriodArithmetic.cs"&gt;
    &lt;DependentUpon&gt;LocalDateTest.cs&lt;/DependentUpon&gt;
  &lt;/Compile&gt;
  </code></pre>
  
  <p>That led to easily-navigable tests:</p>
  
  <p><a href="https://i.stack.imgur.com/mXuFy.png" rel="noreferrer"><img src="https://i.stack.imgur.com/mXuFy.png" alt="Nested tests"></a></p>
  
  <p>I knowingly "lost" this feature when moving to <code>project.json</code> for .NET Core, but had hoped it would return when converting to MSBuild. However, it looks like MSBuild projects based on the .NET Core SDK (root element <code>&lt;Project Sdk="Microsoft.NET.Sdk"&gt;</code>) don't get the same treatment in Visual Studio 2017, even if an <code>ItemGroup</code> is added manually with the same elements as the "old school" project.</p>
  
  <p>ASP.NET Core projects receive automatic nesting for minified CSS and Javascript, but it's not clear how to apply that to C# in .NET Core library projects.</p>