A colleague and I are writing an application that we intend to go Open Source with and are trying to decide on a testing framework. Without integration of NUnit (one of us has resharper while the other does not) we are leaning toward MSTest. However, if the majority of people that work on opensource .net applications only have the express edition of Visual Studio, we may have to change our mind on that.
What version of VS do you use and would MSTest turn you off to an Open Source Project?
Frankly I never heared of anyone using the Express editions. everybody I know or I talked with either use the fully fledged Visual Studio environment, or they use the compiler/libraries from the free SDK and some editor on top of it (CodeWarrior, CodeInsight etc) and rely on some variant of make to build.
As for the test framework, is a double edged sword. I'd recommend NUnit, but then... remember what happened with NDoc?
If I truly felt strongly enough to participate in the Open Source project, MSTest alone wouldn't be enough to turn me away. I'd be willing to adapt to whatever the development tools/environment was.
...and for what it's worth, I use the full version of Visual Studio with Resharper.
Even Microsoft's open source code (Prism/Composite Wpf) doesn't use MSTest. They use NUnit for that project, I believe.
Personally, I'm using VS:TS, so no, test units in MSTest wouldn't turn anything off for me ;), on the other hand, most probably, you will receive different answers from the majority of people, that are not professional programmers as well (working for money doesn't mean you can not work with / on OS projects) (the question is, how many you will find here).
However, if I understand you correctly, you don't want to use nUnit, because you it's not integrated with VS08, you might then check out these projects:
1. http://sourceforge.net/projects/visualnunit/
2. http://sourceforge.net/projects/nunitaddin/
Integrating NUnit with VS08 doesn't seem to the biggest problem, on the other hand, getting VS with built in testing framework might be a bit harder, at least for some people.
You may be able to use visual nunit to add an nunit test runner in VS. link I've never used it but it may be worth a shot.
If your problem is integration with Visual Studio, try Gallio. It includes MbUnit, but its runner can run tests from other frameworks, like NUnit, xUnit, etc.
It would turn me off. See MSBuild, NAnt, NUnit, MSTest, and frustration (not written by me!) - I suspect a number of people feel that way. MSBuild seems like a poorly-done copy of NAnt (we use both), and MSTest likewise looks like Microsoft's usual "not invented here" answer to open source. While I realize that there are good business reasons for Microsoft to develop their own tools, those reasons don't apply to their customers.
There are plug-ins to use NUnit inside Visual Studio without ReSharper, or you can always configure it to run from the Tools menu.
If you don't like NUnit, please consider one of the other open source testing alternatives. See http://stackoverflow.com/questions/261139/nunit-vs-mbunit-vs-mstest-vs-xunit-net