This makes the tests for wibox.hierarchy use test_utils.widget_stub() instead of
having its own implementation of "fake widgets".
Signed-off-by: Uli Schlachter <psychon@znc.in>
A widget hierarchy describes the position of widgets. The hierarchy is a
recursive tree of widget hierarchy instances. This functionality depends on a
:layout function that is not yet implemented on widgets, but will be added
later.
Signed-off-by: Uli Schlachter <psychon@znc.in>