test(langchain): test cache hit/miss on lru

libs/langchain_v1/tests/unit_tests/agents/test_state_schema.py

@@ -10,8 +10,9 @@
 
 from langchain_core.messages import HumanMessage
 from langchain_core.tools import tool
+from typing_extensions import NotRequired, Required
 
-from langchain.agents import create_agent
+from langchain.agents import create_agent, factory
 from langchain.agents.middleware.types import (
     AgentMiddleware,
     AgentState,
@@ -253,3 +254,51 @@ def capture_state_tool(x: int, runtime: ToolRuntime) -> str:
 
     # Verify the agent executed normally
     assert len(result["messages"]) == 4  # Human, AI (tool call), Tool result, AI (final)
+
+
+def test_get_schema_type_hints_cache_hits_for_reused_schema() -> None:
+    """Test repeated schema resolution reuses cached type hints for the same schema."""
+
+    class CachedState(AgentState[Any]):
+        cached_field: str
+        required_field: Required[int]
+        optional_field: NotRequired[Annotated[str, PrivateStateAttr]]
+
+    factory._get_schema_type_hints.cache_clear()
+
+    factory._resolve_schemas({CachedState})
+    first_info = factory._get_schema_type_hints.cache_info()
+    factory._resolve_schemas({CachedState})
+    second_info = factory._get_schema_type_hints.cache_info()
+
+    assert first_info.misses == 1
+    assert first_info.hits == 0
+    assert second_info.misses == 1
+    assert second_info.hits == 1
+
+
+def test_get_schema_type_hints_cache_accepts_distinct_local_schema_types() -> None:
+    """Test locally defined schema classes remain hashable cache keys."""
+    factory._get_schema_type_hints.cache_clear()
+
+    def make_state_schema(name: str) -> type[AgentState[Any]]:
+        class LocalState(AgentState[Any]):
+            value: str
+            required_value: Required[int]
+            optional_private_value: NotRequired[Annotated[str, PrivateStateAttr]]
+
+        LocalState.__name__ = name
+        return LocalState
+
+    schema_a = make_state_schema("LocalStateA")
+    schema_b = make_state_schema("LocalStateB")
+
+    factory._resolve_schemas({schema_a, schema_b})
+    first_info = factory._get_schema_type_hints.cache_info()
+    factory._resolve_schemas({schema_a, schema_b})
+    second_info = factory._get_schema_type_hints.cache_info()
+
+    assert first_info.misses == 2
+    assert first_info.hits == 0
+    assert second_info.misses == 2
+    assert second_info.hits == 2