iter 22b.3.1: fix — quality-review (doc reframe + class-present test)

crates/ail/tests/typeclass_22b3.rs

@@ -47,3 +47,49 @@ fn monomorphise_workspace_is_identity_on_class_free_workspace() {
         );
     }
 }
+
+/// Property: the Task 1 skeleton's class-present branch is also a
+/// no-op. The fixture has a `Def::Class` and a `Def::Instance` (so
+/// the early-out does NOT fire) but no concrete class-method call
+/// sites yet wired through the pipeline; under the skeleton, the
+/// fall-through `Ok(ws.clone())` must preserve every module's
+/// canonical hash.
+///
+/// NOTE: this test will need updating in Task 5 once the skeleton
+/// is replaced with the real fixpoint — at that point synth fns
+/// will be appended to the `defining_module`, breaking module-hash
+/// equality on that module by design. The test as written
+/// guarantees the Task 1 contract and catches accidental partial
+/// rewrites landed before Task 5.
+#[test]
+fn monomorphise_workspace_is_identity_when_no_concrete_call_sites() {
+    // `test_22b2_instance_present.ail.json` has `class Show` +
+    // `instance Show Int` and typechecks cleanly; reused across
+    // 22b.2 tests so its shape is stable.
+    let entry = examples_dir().join("test_22b2_instance_present.ail.json");
+    let ws = ailang_core::load_workspace(&entry).expect("load");
+    let diags = ailang_check::check_workspace(&ws);
+    assert!(diags.is_empty(), "fixture must typecheck: {:?}", diags);
+
+    let ws_after = ailang_check::monomorphise_workspace(&ws)
+        .expect("mono on class-present workspace");
+
+    // Module set unchanged.
+    let before = ailang_core::load_workspace(&entry).expect("re-load");
+    assert_eq!(
+        ws_after.modules.keys().collect::<Vec<_>>(),
+        before.modules.keys().collect::<Vec<_>>(),
+        "module set must be identical"
+    );
+    // Each module hashes byte-identical (skeleton clones unchanged).
+    for (mname, m) in &ws_after.modules {
+        let before_m = &before.modules[mname];
+        let h_after = ailang_core::module_hash(m);
+        let h_before = ailang_core::module_hash(before_m);
+        assert_eq!(
+            h_after, h_before,
+            "class-present module `{}` must hash-identical through Task 1 skeleton",
+            mname
+        );
+    }
+}