avar2 panic failing test

read-fonts/src/tables/fvar.rs

@@ -84,7 +84,9 @@ impl<'a> Fvar<'a> {
         let axis_count = axes.len();
         let mut new_coords = [F2Dot14::ZERO; 64];
         if axis_count > 64 {
-            return; // No avar2 for monster fonts.
+            // No avar2 for monster fonts.
+            // <https://github.com/googlefonts/fontations/issues/1148>
+            return;
         }
         new_coords[..axis_count].copy_from_slice(normalized_coords);
 
@@ -271,4 +273,18 @@ mod tests {
             assert_eq!(normalized_coords[1], F2Dot14::from_f32(expected.1));
         }
     }
+
+    #[test]
+    fn avar2_no_panic_with_wrong_size_coords_array() {
+        // this font has 2 axes
+        let font = FontRef::new(font_test_data::AVAR2_CHECKER).unwrap();
+        let avar = font.avar().ok();
+        let fvar = font.fvar().unwrap();
+        // output array too small
+        let mut normalized_coords = [F2Dot14::default(); 1];
+        fvar.user_to_normalized(avar.as_ref(), [], &mut normalized_coords);
+        // output array too large
+        let mut normalized_coords = [F2Dot14::default(); 4];
+        fvar.user_to_normalized(avar.as_ref(), [], &mut normalized_coords);
+    }
 }