XActLib's tests run into trouble when running in parallel. It's because one test is rebuilding a new Inversion of Control Container (ie Unity) and ServiceLocator – by destroying any previous one – while another test was expecting it to be there. A bit of an issue…
One way to solve it is to turn off parallelization.
using XUnit; ... [assembly: CollectionBehavior(DisableTestParallelization = true)]