Improve filtering for tests that need EGL

This way we don't skip the layout animation tests.

docs/wiki/Packaging-niri.md

@@ -44,6 +44,13 @@ $ export RAYON_NUM_THREADS=2
 
 Don't forget to exclude the development-only `niri-visual-tests` crate when running tests.
 
+Some tests require surfaceless EGL to be available at test time.
+If this is problematic, you can skip them like so:
+
+```
+$ cargo test -- --skip=::egl
+```
+
 You may also want to set the `RUN_SLOW_TESTS=1` environment variable to run the slower tests.
 
 ### Version string

flake.nix

@@ -118,7 +118,7 @@
           checkFlags = [
             # These tests require the ability to access a "valid EGL Display", but that won't work
             # inside the Nix sandbox
-            "--skip=tests::animations"
+            "--skip=::egl"
           ];
 
           postInstall =

src/tests/animations.rs

@@ -124,7 +124,7 @@ fn set_up_two_in_column() -> (Fixture, ClientId, WlSurface, WlSurface) {
 }
 
 #[test]
-fn height_resize_animates_next_y() {
+fn egl_height_resize_animates_next_y() {
     let (mut f, id, surface1, surface2) = set_up_two_in_column();
 
     // Issue a resize.
@@ -171,7 +171,7 @@ fn height_resize_animates_next_y() {
 }
 
 #[test]
-fn clientside_height_change_doesnt_animate() {
+fn egl_clientside_height_change_doesnt_animate() {
     let (mut f, id, surface1, _surface2) = set_up_two_in_column();
 
     // The initial state.