Validate not empty (#1957)

libs/checkpoint/langgraph/store/base/__init__.py

@@ -159,11 +159,15 @@ class InvalidNamespaceError(ValueError):
 
 
 def _validate_namespace(namespace: tuple[str, ...]) -> None:
+    if not namespace:
+        raise ValueError("Namespace cannot be empty.")
     for label in namespace:
         if "." in label:
             raise InvalidNamespaceError(
                 f"Invalid namespace label '{label}'. Namespace labels cannot contain periods ('.')."
             )
+        elif not label:
+            raise ValueError("Namespace labels cannot be empty strings.")
 
 
 class BaseStore(ABC):

libs/checkpoint/tests/test_store.py

@@ -2,9 +2,10 @@ import asyncio
 from datetime import datetime
 from typing import Iterable
 
+import pytest
 from pytest_mock import MockerFixture
 
-from langgraph.store.base import GetOp, Item, Op, Result
+from langgraph.store.base import GetOp, InvalidNamespaceError, Item, Op, Result
 from langgraph.store.base.batch import AsyncBatchedBaseStore
 from langgraph.store.memory import InMemoryStore
 
@@ -259,3 +260,26 @@ def test_list_namespaces_empty_store() -> None:
 
     result = store.list_namespaces()
     assert result == []
+
+
+async def test_cannot_put_empty_namespace() -> None:
+    store = InMemoryStore()
+    doc = {"foo": "bar"}
+
+    with pytest.raises(InvalidNamespaceError):
+        store.put([], "foo", doc)
+
+    with pytest.raises(InvalidNamespaceError):
+        await store.aput([], "foo", doc)
+
+    with pytest.raises(InvalidNamespaceError):
+        store.put(["the", "thing.about"], "foo", doc)
+
+    with pytest.raises(InvalidNamespaceError):
+        await store.aput(["the", "thing.about"], "foo", doc)
+
+    with pytest.raises(InvalidNamespaceError):
+        store.put(["some", "fun", ""], "foo", doc)
+
+    with pytest.raises(InvalidNamespaceError):
+        await store.aput(["some", "fun", ""], "foo", doc)