To make this practical to use in a template, we want relations in both
directions. And at least for consistency with other things, these fields
should contain the `Argument` instead of just its name string.
So we need to do this after are the arguments in the message have been
initially parsed. Adding these fields when parsing the request/event
close tag seems to work well enough.
Co-authored-by: Peter Hutterer <peter.hutterer@who-t.net>
This is a bit convoluted because ei-scanner is named like that, so it
cannot be imported as python module. The solution for that is to
copy/rename it with meson to the builddir and run pytest in that. This
also allows us to set the path to the protocol XML file while we're at
it so we can use it as a fixture.
Actual tests are minimal for now, can be extended over time.
