test: clarify feature implementation status

rabby-core/src/feature/mod.rs

@@ -1,5 +1,6 @@
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum FeatureStatus {
+    Implemented,
     Modeled,
     UiPrototype,
     Planned,
@@ -188,6 +189,13 @@ pub fn feature_matrix() -> Vec<(&'static str, &'static str)> {
         .collect()
 }
 
+pub fn features_by_status(status: FeatureStatus) -> Vec<&'static FeatureSpec> {
+    TABBY_FEATURES
+        .iter()
+        .filter(|feature| feature.status == status)
+        .collect()
+}
+
 pub fn missing_required_features<'a>(required_keys: &'a [&'a str]) -> Vec<&'a str> {
     required_keys
         .iter()
@@ -262,4 +270,14 @@ mod tests {
             "scaffold should not imply every Tabby feature is complete"
         );
     }
+
+    #[test]
+    fn status_queries_distinguish_implemented_from_modeled() {
+        assert!(features_by_status(FeatureStatus::Implemented).is_empty());
+        let modeled = features_by_status(FeatureStatus::Modeled);
+        assert!(modeled.iter().any(|feature| feature.key == "nested-splits"));
+        assert!(modeled
+            .iter()
+            .all(|feature| feature.status == FeatureStatus::Modeled));
+    }
 }