This is an intermediate step to have smaller unit tests. It is a trade off
between having many many test executables compared to a few bigger ones. But
this comes a lot closer to what QtTest is meant to be used.
Summary:
I wanted to rename xbus because its relation to //swift// is not immediately clear from the name.
xswiftbus seems reasonable.
Reviewers: #swift_pilot_client, kbasan
Reviewed By: kbasan
Subscribers: kbasan, jenkins
Tags: #swift_pilot_client
Differential Revision: https://dev.swift-project.org/D14