can we maybe extend the pattern list in the filetype_extensions.conf used for the unittests on the fly?
We'd have to update `filetype_extensions.conf`, run unit tests, and then revert back to the original `filetype_extensions.conf`. If someone interrupts the unit test by Ctrl+C, the original version wouldn't be restored which makes this approach a little fragile.
Not less ugly but more temporary:
There's always the option of a very elegant and permanent solution - not to have a unit test for meson at all :-)