anthropic[patch]: add benchmark (#31718)

Account for lazy loading of clients in init time benchmark

libs/partners/anthropic/tests/unit_tests/test_standard.py

@@ -1,7 +1,9 @@
 """Standard LangChain interface tests"""
 
+import pytest
 from langchain_core.language_models import BaseChatModel
 from langchain_tests.unit_tests import ChatModelUnitTests
+from pytest_benchmark.fixture import BenchmarkFixture  # type: ignore[import-untyped]
 
 from langchain_anthropic import ChatAnthropic
 
@@ -14,3 +16,16 @@ class TestAnthropicStandard(ChatModelUnitTests):
     @property
     def chat_model_params(self) -> dict:
         return {"model": "claude-3-haiku-20240307"}
+
+
+@pytest.mark.benchmark
+def test_init_time_with_client(benchmark: BenchmarkFixture) -> None:
+    """Test initialization time, accounting for lazy loading of client."""
+
+    def _init_in_loop_with_clients() -> None:
+        for _ in range(10):
+            llm = ChatAnthropic(model="claude-3-5-haiku-latest")
+            _ = llm._client
+            _ = llm._async_client
+
+    benchmark(_init_in_loop_with_clients)