title: Including files with directory specified separately in MSBuild
body: <p>This seems like it should be simple but I can't work it out from the reference and my google-fu is apparently weak.</p>
  
  <p>I just want to specify the file names and base folder separately in the build file...</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003"&gt;
    &lt;PropertyGroup&gt;
      &lt;TestFilesWithFolder&gt;
        B:\Root\Test1.*;
        B:\Root\Test2.*
      &lt;/TestFilesWithFolder&gt;
      &lt;TestFiles&gt;Test1.*;Test2.*&lt;/TestFiles&gt;
      &lt;TestFileRoot&gt;B:\Root&lt;/TestFileRoot&gt;
    &lt;/PropertyGroup&gt;
    &lt;Target Name="Build"&gt;
      &lt;ItemGroup&gt;
        &lt;TestFilesGroupWithFolder Include="$(TestFilesWithFolder)" /&gt;
        &lt;TestFilesGroup Include="$(TestFileRoot)\$(TestFiles)" /&gt;
      &lt;/ItemGroup&gt;
      &lt;Warning Text="Source files with folder: @(TestFilesGroupWithFolder)" /&gt;
      &lt;Warning Text="Source files: @(TestFilesGroup)" /&gt;
    &lt;/Target&gt;
  &lt;/Project&gt;
  </code></pre>
  
  <p>When I run this, the first warning shows both files as expected, but the second warning only shows the first file (since the straight string concat put the folder name on the first but not second).</p>
  
  <p>How would I get the ItemGroup "TestFilesGroup" to include both the files given the "TestFiles" and "TestFileRoot" properties?</p>