diff --git a/src/tests.ts b/src/tests.ts
index af9b93f..7d7278c 100644
--- a/src/tests.ts
+++ b/src/tests.ts
@@ -28,6 +28,15 @@ const Identifiable = <ID>() => trait
     })
     .build()
 
+const ImplementsIdentifiable = <ID>(defaultID: ID) => expression
+    .expresses(Identifiable<ID>())
+    .build()
+    .subtrait()
+        .implement(Super => class ImplementsIdentifiable extends Super {
+            readonly id = defaultID
+        })
+        .build()
+
 const StatefulSubscription = trait
     .abstract(Super => class extends Super {
         declare readonly isStatefulSubscription: true