Well, the tests are being run in a different VM instance, so it shouldn't be a problem here.
Even so, I would shutdown the thread pool, problem is, ScalaCheck does not have post test hooks where I could do this (I think that ScalaCheck evaluates tests lazily after the constructor, so shutting down the pool in the ctor won't work). However, even if I could do that, I would have to do something like this:

      ec.asInstanceOf[scala.concurrent.impl.ExecutionContextImpl].executor.asInstanceOf[java.util.concurrent.ThreadPoolExecutor].shutdown()

And the problem with that is that `ExecutionContextImpl` is package private, and tests can only be in the root level package in partest.