title: How important is Visual Studio's .vsmdi file?
body: <p>Here's the scenario: </p>
  
  <p>'User A' has created unit tests through Visual Studio 2010.  The test project and unit test source code have been checked into version control.  'User B' gets the test project and unit test source code from version control.  'User B' then opens the test project and receives a message saying "Error loading blah.blah.blah.vsmdi: Input file not found: blah.blah.blah.vsmdi."  However, 'User B' can still run the unit tests successfully.</p>
  
  <p>Now, regardless of whether 'User A' <em>should</em> have checked in the .vsmdi file, there don't appear to be any negative effects, other than the error message.</p>
  
  <p>Is there any harm in not having the .vsmdi file?  Or, conversely, what is the benefit of having the .vsmdi file?</p>