diff --git a/.gitignore b/.gitignore
index 505a3b1..1f8f3c6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,3 +8,6 @@ wheels/
 
 # Virtual environments
 .venv
+
+
+*.ipynb
\ No newline at end of file
diff --git a/tests/test_mapping.py b/tests/test_mapping.py
index 08f66fe..f1571f0 100644
--- a/tests/test_mapping.py
+++ b/tests/test_mapping.py
@@ -1,3 +1,4 @@
+from hooked_containers import events as e
 from hooked_containers.mapping import HookedMapping
 
 
@@ -25,14 +26,24 @@ class TestHookedMapping:
     class TestMappingOps:
         def test_setitem(self):
             added = []
-            m = HookedMapping({}, lambda e: added.append(e.item))
+
+            def hook(event: e.ChangeEvent):
+                assert isinstance(event, e.AddItemEvent)
+                added.append(event.item)
+
+            m = HookedMapping({}, hook)
             m["a"] = 1
             assert m._data == {"a": 1}
             assert added == [1]
 
         def test_nested_setitem(self):
             added = []
-            m = HookedMapping({"a": {}}, lambda e: added.append(e.item))
+
+            def hook(event: e.ChangeEvent):
+                assert isinstance(event, e.AddItemEvent)
+                added.append(event.item)
+
+            m = HookedMapping({"a": {}}, hook)
             m["a"]["x"] = 1
             assert m._data == {"a": {"x": 1}}
             assert added == [1]