[simple] added test case and improve self class return type annotation (#3773)

a simple follow up of https://github.com/hwchase17/langchain/pull/3748
- added test case
- improve annotation when function return type is class itself.

tests/integration_tests/retrievers/document_compressors/test_chain_extract.py

@@ -4,6 +4,14 @@ from langchain.retrievers.document_compressors import LLMChainExtractor
 from langchain.schema import Document
 
 
+def test_llm_construction_with_kwargs() -> None:
+    llm_chain_kwargs = {"verbose": True}
+    compressor = LLMChainExtractor.from_llm(
+        ChatOpenAI(), llm_chain_kwargs=llm_chain_kwargs
+    )
+    assert compressor.llm_chain.verbose is True
+
+
 def test_llm_chain_extractor() -> None:
     texts = [
         "The Roman Empire followed the Roman Republic.",