Refactor GLib.io_add_watch to make it more testable
Refactor GLib.io_add_watch to make it more testable

Break the argument munging code into a separate function which
can be tested in isolation of adding an io watch.
Add additional failing test which specifies all args as keywords
which we eventually need to support for consistency with the
rest of PyGObject.

https://bugzilla.gnome.org/show_bug.cgi?id=640812

davibe/pygobject,davibe/pygobject,sfeltman/pygobject,sfeltman/pygobject,pexip/pygobject,GNOME/pygobject,GNOME/pygobject,pexip/pygobject,GNOME/pygobject,sfeltman/pygobject,davibe/pygobject,pexip/pygobject,davibe/pygobject