Tests should be divided up by the environment they require in order to operate
correctly.

Where to put new tests:

* /tests/ if they're simple regression tests in pure C++ that don't access
  D-Bus (these are likely to be rare)

* /tests/dbus/ if they touch the session bus (a temporary session bus will be
  used)

/tests/lib/ contains support code, some of it taken from the telepathy-glib
examples and regression tests.