Assertions not executed in test_stream_error_callback

[cbornet]

Checked other resources

• I added a very descriptive title to this issue.
• I searched the LangChain documentation with the integrated search.
• I used the GitHub search to find a similar question and didn't find it.
• I am sure that this is a bug in LangChain rather than my code.
• The bug is not resolved by updating to the latest stable version of LangChain (or the specific integration package).

Example Code

N/A

Error Message and Stack Trace (if applicable)

No response

Description

test_stream_error_callback has test code which is not executed.

async def test_stream_error_callback() -> None:
    message = "test"

    def eval_response(callback: BaseFakeCallbackHandler, i: int) -> None:
        assert callback.errors == 1
        assert len(callback.errors_args) == 1
        llm_result: LLMResult = callback.errors_args[0]["kwargs"]["response"]
        if i == 0:
            assert llm_result.generations == []
        else:
            assert llm_result.generations[0][0].text == message[:i]

    for i in range(2):
        llm = FakeListChatModel(
            responses=[message],
            error_on_chunk_number=i,
        )
        with pytest.raises(FakeListChatModelError):
            cb_async = FakeAsyncCallbackHandler()
            async for _ in llm.astream("Dummy message", callbacks=[cb_async]):
                pass
            # !!! The code below is not executed
            eval_response(cb_async, i)

            cb_sync = FakeCallbackHandler()
            for _ in llm.stream("Dumy message", callbacks=[cb_sync]):
                pass

            eval_response(cb_sync, i)

when llm.astream is called it raises FakeListChatModelError and exits the with section without executing eval_response and the sync test.
This was detected when applying ruff rule PT012. See #29381.

System Info

N/A