perf(langchain): add another init test with middleware (#36644)

add another init test with middleware

libs/langchain_v1/tests/benchmarks/test_create_agent.py

@@ -1,9 +1,21 @@
+from typing import TYPE_CHECKING, Any
+
 import pytest
 from langchain_core.language_models.fake_chat_models import GenericFakeChatModel
 from langchain_core.messages import AIMessage
 from pytest_benchmark.fixture import BenchmarkFixture
 
 from langchain.agents import create_agent
+from langchain.agents.middleware import (
+    ModelRetryMiddleware,
+    TodoListMiddleware,
+    ToolRetryMiddleware,
+)
+
+if TYPE_CHECKING:
+    from collections.abc import Sequence
+
+    from langchain.agents.middleware import AgentMiddleware
 
 
 @pytest.mark.benchmark
@@ -12,3 +24,21 @@ def test_create_agent_instantiation(benchmark: BenchmarkFixture) -> None:
         create_agent(model=GenericFakeChatModel(messages=iter([AIMessage(content="ok")])))
 
     benchmark(instantiate_agent)
+
+
+@pytest.mark.benchmark
+def test_create_agent_instantiation_with_middleware(
+    benchmark: BenchmarkFixture,
+) -> None:
+    def instantiate_agent() -> None:
+        middleware: Sequence[AgentMiddleware[Any, Any]] = (
+            TodoListMiddleware(),
+            ToolRetryMiddleware(),
+            ModelRetryMiddleware(),
+        )
+        create_agent(
+            model=GenericFakeChatModel(messages=iter([AIMessage(content="ok")])),
+            middleware=middleware,
+        )
+
+    benchmark(instantiate_agent)