Hi Victor
So far as I know, MSTest executes tests one by one. It executes the next test only if the previous one is returned. Thus it's likely to be a problem in ArtOfTest. It seems you are invoking tests created with ArtOfTest in MSTest. I haven't tried ArtOfTest, but I guess test methods created by ArtOfTest might be asynchronously. They returned even if they are not finished. Please confirm this with ArtOfTest.
And MSTest is the only tool to run testlist.