Python test cases don't show up in the visual studio Test Explorer if the test case method has a custom python decorator on it. For example the following test method would NOT be "discovered" by the adapter in PTVS,
a = 1 + 2
But if I remove the decorators it does show in the VS Test Explorer.
I'm currently reviewing PTVS 2.0 RC for VS2012 SP3 with Python 3.2 and looking into the Test Explorer integration with the new Test Adapter in this release (when compared with PTVS v1.5).