test: use timezone-aware datetimes

Co-authored-by: afarntrog <47332252+afarntrog@users.noreply.github.com>

Author: Copilot

src/strands/session/repository_session_manager.py

@@ -47,10 +47,11 @@ def __init__(
         self.session_repository = session_repository
         self.session_id = session_id
         self.state_serializer = state_serializer or JsonStateSerializer()
-        if not getattr(self.state_serializer, "name", None):
+        serializer_name = getattr(self.state_serializer, "name", "")
+        if not isinstance(serializer_name, str) or not serializer_name.strip():
             raise ValueError("state_serializer.name must be a non-empty string")
         self.state_serializer_registry: dict[str, StateSerializer] = {
-            self.state_serializer.name: self.state_serializer
+            serializer_name: self.state_serializer
         }
         if state_serializer_registry:
             self.state_serializer_registry.update(state_serializer_registry)

tests/strands/agent/test_agent_state.py

@@ -86,9 +86,9 @@ def test_json_serializable_values():
 def test_non_json_values_allowed_by_default():
     """Non-JSON values are allowed when validation is disabled."""
     state = AgentState()
-    from datetime import datetime
+    from datetime import datetime, timezone
 
-    marker = datetime.utcnow()
+    marker = datetime.now(timezone.utc)
     state.set("obj", marker)
     assert state.get("obj") == marker
 

tests/strands/types/test_json_dict.py

@@ -82,9 +82,9 @@ def test_json_serializable_values():
 def test_non_json_values_allowed_by_default():
     """Non-JSON values are allowed when validation is disabled."""
     state = JSONSerializableDict()
-    from datetime import datetime
+    from datetime import datetime, timezone
 
-    marker = datetime.utcnow()
+    marker = datetime.now(timezone.utc)
     state.set("obj", marker)
     assert state.get("obj") == marker
 

tests/strands/types/test_state_serializers.py

@@ -1,11 +1,11 @@
-from datetime import datetime
+from datetime import datetime, timezone
 
 from strands.types.state_serializers import JsonStateSerializer, PickleStateSerializer
 
 
 def test_json_state_serializer_drops_non_serializable():
     serializer = JsonStateSerializer()
-    state = {"a": 1, "dt": datetime.utcnow()}
+    state = {"a": 1, "dt": datetime.now(timezone.utc)}
 
     serialized = serializer.serialize(state)