Xvfb
Thanks.
Why do you execute the tests at all?
Basically, I saw no reason to disable anything inside Geany's test suite until now, or disabling running the test suite altogether (but then again, it's only since a couple months that I'm active to some degree in nixpkgs). It was enabled since Geany's [initial addition](https://github.com/NixOS/nixpkgs/commit/51fe78841797c3d59ed7289df28ed19715c9...) to nixpkgs and seems to have been fine since.[^1][^2] The rest is just me liking to get to the bottom of things sometimes. ^^;
I think it doesn't hurt to run Geany's suite in nixpkgs as it's relatively quick and lightweight—as long as it doesn't break things and cause additional maintenance burden.
[^1]: Some context: running upstream test suites is by default disabled in nixpkgs; package(r)s have to explicitly opt into this, ordinarily with `doCheck = true;`. There was come discussion around enabling this by default, as there are arguably good reasons for both approaches (notably https://github.com/NixOS/nixpkgs/issues/33599 and https://github.com/NixOS/rfcs/pull/95), but it seems to have petered out. [^2]: But "we've always been doing it this way" is never a good argument.