linux: enable test TextSystem (#9037)

Make text tests work on linux.

crates/gpui/src/platform/test.rs

@@ -7,6 +7,6 @@ mod window;
 pub(crate) use dispatcher::*;
 pub(crate) use display::*;
 pub(crate) use platform::*;
-#[cfg(not(target_os = "macos"))]
+#[cfg(target_os = "windows")]
 pub(crate) use text_system::*;
 pub(crate) use window::*;

crates/gpui/src/platform/test/platform.rs

@@ -121,7 +121,7 @@ impl Platform for TestPlatform {
 
     fn text_system(&self) -> Arc<dyn PlatformTextSystem> {
         #[cfg(target_os = "linux")]
-        return Arc::new(crate::platform::test::TestTextSystem {});
+        return Arc::new(crate::platform::linux::LinuxTextSystem::new());
 
         #[cfg(target_os = "macos")]
         return Arc::new(crate::platform::mac::MacTextSystem::new());

crates/gpui/src/text_system.rs

@@ -63,7 +63,10 @@ impl TextSystem {
                 // TODO: This is currently Zed-specific.
                 // We should allow GPUI users to provide their own fallback font stack.
                 font("Zed Mono"),
-                font("Helvetica")
+                font("Helvetica"),
+                font("Cantarell"), // Gnome
+                font("Ubuntu"),    // Gnome (Ubuntu)
+                font("Noto Sans"), // KDE
             ],
         }
     }