test_fixed_message_response_when_no_docs_found() — langchain Function Reference

Source Code

libs/langchain/tests/unit_tests/chains/test_conversation_retrieval.py lines 65–87

def test_fixed_message_response_when_no_docs_found() -> None:
    fixed_resp = "I don't know"
    answer = "I know the answer!"
    llm = FakeListLLM(responses=[answer])
    retriever = SequentialRetriever(sequential_responses=[[]])
    memory = ConversationBufferMemory(
        k=1,
        output_key="answer",
        memory_key="chat_history",
        return_messages=True,
    )
    qa_chain = ConversationalRetrievalChain.from_llm(
        llm=llm,
        memory=memory,
        retriever=retriever,
        return_source_documents=True,
        rephrase_question=False,
        response_if_no_docs_found=fixed_resp,
        verbose=True,
    )
    got = qa_chain("What is the answer?")
    assert got["chat_history"][1].content == fixed_resp
    assert got["answer"] == fixed_resp