Dave Donaldson

If you're using one of the VS2005 editions that have the built-in unit test capability, you've no doubt probably noticed that Visual Studio adds a file to your solution named [SolutionName].vsmdi. This vsmdi file is actually nothing more than an XML document that contains all of your unit tests and the test lists they are contained in, if you've organized your tests in such a way. The vsmdi file is what Test Manager uses to display and manage all your unit tests.

But what I've experienced is that developers tend to organize their unit tests differently, and rightfully so. Hence, this is the reason why you should not put the vsmdi file under source control. If you do put this file under source control, you'll end up overwriting other developers test lists, or they'll overwrite your test lists, all of which is a real nuisance. Plus, Visual Studio then likes to create more vsmdi files by appending an incremented number to the file name, but I haven't quite figured out exactly when/why it does that, but it seems to definitely be related to when the vsmdi file is under source control.

The vsmdi file is user-specific, so my advice is to exclude the vsmdi file from source control so that each developer maintains his own list of tests for however it best makes sense to each individual developer.