From f8ffab72e2a723baeec3e2816221929cddfd2208 Mon Sep 17 00:00:00 2001
From: Ian Holloway <72767437+IanHollow@users.noreply.github.com>
Date: Sun, 18 Oct 2026 06:38:06 -0700
Subject: [PATCH] Tests: keep font-cache misses independent of optional Thai
 fonts (#1981)

Assisted-by: GPT-6

Signed-off-by: IanHollow <72767437+IanHollow@users.noreply.github.com>
---
 crates/fonts/src/tests_sysfonts.rs | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/crates/fonts/src/tests_sysfonts.rs b/crates/fonts/src/tests_sysfonts.rs
index 83013e7b7c..19b36be188 100644
--- a/crates/fonts/src/tests_sysfonts.rs
+++ b/crates/fonts/src/tests_sysfonts.rs
@@ -162,21 +162,26 @@ fn fallback_lookups_are_remembered_until_fonts_load() {
     let db = FontDb::with_font_dirs(vec![dir]);
     db.set_system_fallback(false);
     let latin = db.face(FALLBACK_FAMILY, "Regular");
-    let thai = 'ก';
-    assert!(db.fallback_for(thai, latin.id()).is_none(), "no bundled Thai font");
+    // A cache-miss fixture must stay absent even when Thai Craft fonts are embedded.
+    // The coverage-index regression below also uses this supplementary private-use range.
+    let missing = '\u{F0001}';
+    assert!(db.fallback_for(missing, latin.id()).is_none(), "no bundled font covers the cache-miss fixture");
+    if crate::CRAFT_FONTS.iter().any(|font| font.scripts.contains(&"Thai")) {
+        assert!(db.fallback_for('ก', latin.id()).is_some(), "the embedded Thai face supplies its glyph");
+    }
     let a = db.fallback_for('A', latin.id()).unwrap();
     assert_eq!(db.fallback_for('A', latin.id()).unwrap().id(), a.id(), "the same answer from the cache");
     {
         let cache = db.fallbacks.read().unwrap();
         assert_eq!(cache.faces, db.read_faces().len());
-        assert!(cache.map.contains_key(&(thai, latin.id())) && cache.map.contains_key(&('A', latin.id())));
+        assert!(cache.map.contains_key(&(missing, latin.id())) && cache.map.contains_key(&('A', latin.id())));
     }
     // Loading fonts (here, the installed family) makes the remembered answers stale.
     assert_eq!(db.face(FAMILY, "Regular").family, FAMILY);
     assert_eq!(db.fallback_for('A', latin.id()).unwrap().id(), a.id());
     let cache = db.fallbacks.read().unwrap();
     assert_eq!(cache.faces, db.read_faces().len());
-    assert!(!cache.map.contains_key(&(thai, latin.id())), "entries from before the fonts loaded are dropped");
+    assert!(!cache.map.contains_key(&(missing, latin.id())), "entries from before the fonts loaded are dropped");
 }
 
 #[test]
@@ -282,8 +287,12 @@ fn fallback_cache_is_dropped_when_a_face_loads_by_its_legacy_family_name() {
     let db = FontDb::with_font_dirs(vec![dir]);
     db.set_system_fallback(false);
     let latin = db.face(FALLBACK_FAMILY, "Regular");
-    let thai = 'ก';
-    assert!(db.fallback_for(thai, latin.id()).is_none());
+    // Keep the negative cache entry independent of the optional Thai font input.
+    let missing = '\u{F0001}';
+    assert!(db.fallback_for(missing, latin.id()).is_none());
+    if crate::CRAFT_FONTS.iter().any(|font| font.scripts.contains(&"Thai")) {
+        assert!(db.fallback_for('ก', latin.id()).is_some(), "the embedded Thai face supplies its glyph");
+    }
     let before = db.read_faces().len();
     let semibold = format!("{FAMILY} Semibold");
     let f = db.face(&semibold, "Regular");
@@ -292,7 +301,7 @@ fn fallback_cache_is_dropped_when_a_face_loads_by_its_legacy_family_name() {
     assert!(db.fallback_for('A', f.id()).is_some_and(|g| g.id() != f.id()));
     let cache = db.fallbacks.read().unwrap();
     assert_eq!(cache.faces, db.read_faces().len());
-    assert!(!cache.map.contains_key(&(thai, latin.id())), "answers from before the load are dropped");
+    assert!(!cache.map.contains_key(&(missing, latin.id())), "answers from before the load are dropped");
 }
 
 #[test]