Add unit test for overridden lc_namespace (#16093)

libs/langchain/tests/unit_tests/load/__snapshots__/test_dump.ambr

@@ -30,10 +30,9 @@
     "lc": 1,
     "type": "constructor",
     "id": [
-      "tests",
-      "unit_tests",
-      "load",
-      "test_dump",
+      "my",
+      "special",
+      "namespace",
       "SpecialPerson"
     ],
     "kwargs": {

libs/langchain/tests/unit_tests/load/test_dump.py

@@ -1,6 +1,6 @@
 """Test for Serializable base class"""
 
-from typing import Any, Dict
+from typing import Any, Dict, List
 
 import pytest
 from langchain_community.chat_models.openai import ChatOpenAI
@@ -37,6 +37,10 @@ class SpecialPerson(Person):
 
     another_visible: str = "bye"
 
+    @classmethod
+    def get_lc_namespace(cls) -> List[str]:
+        return ["my", "special", "namespace"]
+
     # Gets merged with parent class's secrets
     @property
     def lc_secrets(self) -> Dict[str, str]:
@@ -58,6 +62,7 @@ def test_person(snapshot: Any) -> None:
     sp = SpecialPerson(another_secret="Wooo", secret="Hmm")
     assert dumps(sp, pretty=True) == snapshot
     assert Person.lc_id() == ["tests", "unit_tests", "load", "test_dump", "Person"]
+    assert SpecialPerson.lc_id() == ["my", "special", "namespace", "SpecialPerson"]
 
 
 def test_typeerror() -> None: