How to run a subset of the unit tests with Xcode 4

Xcode 4 introduces the scheme feature. With which you can create different schemes for your project. Under the test item in a scheme you can select which tests to run. However, I'm finding that all the tests are run, not just the ones I'm selecting. How can I just run a subset of my unit tests?

I suspect my problem is related to the fact that my project and unit te开发者_开发技巧sts were originally created with Xcode 3 and imported into Xcode 4.

There was an earlier question about this sort of problem, but my question is specifically about Xcode 4.0.2.

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This was fixed in a post 4.0 release of Xcode. I'm using 4.5 and it is fixed this release, but I don't know the exact release it was fixed in.