[BugFix] Fix two stop reason for multimodal output (#3374)

Signed-off-by: Mike_Qiu <qiudayu.qdy@antgroup.com>
Signed-off-by: Mike Qiu <qdy220091330@gmail.com>
Co-authored-by: Mike_Qiu <qiudayu.qdy@antgroup.com>
Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>
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authored and GitHub committed 2026-06-01 21:51:29 +08:00
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# SPDX-License-Identifier: Apache-2.0
"""Tests for multi-modal streaming finish_reason behavior (commit 44c799bc).
Verifies that the /v1/chat/completions streaming endpoint emits exactly one
finish_reason="stop" per choice when multiple output modalities (text, audio)
are active, complying with the OpenAI streaming spec.
Key invariants tested:
- Single modality (text only): last chunk carries finish_reason="stop"
- Multi-modality (text+audio): only the final modality chunk carries
finish_reason="stop"; earlier finishing modalities emit finish_reason=null
- n>1 with multi-modality: each choice independently tracks its own
modality state, so each choice gets exactly one "stop"
- Engine skips a declared modality: fallback stop chunk is emitted at
stream end so the client always receives finish_reason="stop"
- voice/speaker parameter compatibility in chat completions
"""
import enum
import json
from unittest.mock import MagicMock
import pytest
# Python 3.10 compat: StrEnum was added in 3.11
if not hasattr(enum, "StrEnum"):
class _StrEnum(str, enum.Enum):
"""Minimal StrEnum backport for Python 3.10."""
enum.StrEnum = _StrEnum # type: ignore[attr-defined]
from vllm.entrypoints.openai.chat_completion.protocol import (
ChatCompletionRequest,
ChatCompletionResponseStreamChoice,
)
from vllm.entrypoints.openai.engine.protocol import DeltaMessage
from vllm.entrypoints.openai.models.serving import OpenAIServingModels
from vllm.outputs import CompletionOutput, RequestOutput
from vllm_omni.entrypoints.openai.serving_chat import OmniOpenAIServingChat
from vllm_omni.outputs import OmniRequestOutput
pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------
def _make_text_omni_output(
request_id: str = "test-req",
text: str = "hello",
token_ids: list[int] | None = None,
finish_reason: str | None = None,
index: int = 0,
num_prompt_tokens: int = 3,
) -> OmniRequestOutput:
"""Build an OmniRequestOutput wrapping a text RequestOutput."""
if token_ids is None:
token_ids = [10, 11, 12]
res = RequestOutput(
request_id=request_id,
prompt="test",
prompt_token_ids=list(range(num_prompt_tokens)),
prompt_logprobs=None,
outputs=[
CompletionOutput(
index=index,
text=text,
token_ids=token_ids,
cumulative_logprob=0.0,
logprobs=None,
finish_reason=finish_reason,
stop_reason=None,
)
],
finished=finish_reason is not None,
)
return OmniRequestOutput(
request_id=request_id,
final_output_type="text",
request_output=res,
finished=finish_reason is not None,
)
def _make_audio_omni_output(
request_id: str = "test-req",
index: int = 0,
num_prompt_tokens: int = 3,
) -> OmniRequestOutput:
"""Build an OmniRequestOutput for audio (no torch dependency)."""
res = RequestOutput(
request_id=request_id,
prompt="test",
prompt_token_ids=list(range(num_prompt_tokens)),
prompt_logprobs=None,
outputs=[
CompletionOutput(
index=index,
text="",
token_ids=[],
cumulative_logprob=0.0,
logprobs=None,
finish_reason="stop",
stop_reason=None,
)
],
finished=True,
)
return OmniRequestOutput(
request_id=request_id,
final_output_type="audio",
request_output=res,
finished=True,
)
def _mock_audio_choices(index: int = 0, role: str = "assistant"):
return [
ChatCompletionResponseStreamChoice(
index=index,
delta=DeltaMessage(role=role, content="dGVzdA=="),
logprobs=None,
finish_reason="stop",
)
]
def _build_serving_chat():
"""Create a minimal OmniOpenAIServingChat for testing."""
mock_engine = MagicMock()
mock_engine.errored = False
models = OpenAIServingModels(
engine_client=mock_engine,
base_model_paths=[],
)
mock_render = MagicMock()
instance = OmniOpenAIServingChat(
engine_client=mock_engine,
models=models,
response_role="assistant",
openai_serving_render=mock_render,
request_logger=None,
chat_template=None,
chat_template_content_format="auto",
)
instance._create_audio_choice = MagicMock(
side_effect=lambda omni_res, role, request, stream=False: _mock_audio_choices(
index=omni_res.request_output.outputs[0].index,
role=role,
)
)
return instance
def _make_request(modalities: list[str], n: int = 1) -> ChatCompletionRequest:
req = ChatCompletionRequest(
model="test-model",
messages=[{"role": "user", "content": "hello"}],
n=n,
stream=True,
)
req.modalities = modalities # type: ignore[attr-defined]
return req
def _parse_sse_chunks(lines: list[str]) -> list[dict]:
"""Parse SSE lines into JSON dicts."""
prefix = "data: "
chunks = []
for line in lines:
line = line.strip()
if not line.startswith(prefix):
continue
payload = line[len(prefix) :].strip()
if payload == "[DONE]":
continue
try:
chunks.append(json.loads(payload))
except json.JSONDecodeError:
pass
return chunks
async def _collect_stream(gen):
result = []
async for item in gen:
result.append(item)
return result
# ---------------------------------------------------------------------------
# Tests: finish_reason correctness
# ---------------------------------------------------------------------------
@pytest.mark.asyncio
async def test_single_modality_text_only_one_stop():
"""Text-only streaming: exactly one chunk has finish_reason='stop'."""
serving_chat = _build_serving_chat()
request = _make_request(modalities=["text"])
async def result_generator():
yield _make_text_omni_output(text="he", token_ids=[10, 11], finish_reason=None)
yield _make_text_omni_output(text="llo", token_ids=[12], finish_reason="stop")
raw_lines = await _collect_stream(
serving_chat.chat_completion_stream_generator(
request=request,
result_generator=result_generator(),
request_id="test-req",
model_name="test-model",
conversation=[],
tokenizer=MagicMock(),
request_metadata=MagicMock(),
)
)
chunks = _parse_sse_chunks(raw_lines)
finish_reasons = [c["choices"][0]["finish_reason"] for c in chunks if c.get("choices")]
assert finish_reasons[-1] == "stop"
assert finish_reasons.count("stop") == 1
for fr in finish_reasons[:-1]:
assert fr is None
@pytest.mark.asyncio
async def test_multi_modal_text_audio_only_last_stop():
"""text+audio: text finish sends finish_reason=null, audio sends stop."""
serving_chat = _build_serving_chat()
request = _make_request(modalities=["text", "audio"])
async def result_generator():
yield _make_text_omni_output(text="he", token_ids=[10, 11], finish_reason=None)
yield _make_text_omni_output(text="llo", token_ids=[12], finish_reason="stop")
yield _make_audio_omni_output()
raw_lines = await _collect_stream(
serving_chat.chat_completion_stream_generator(
request=request,
result_generator=result_generator(),
request_id="test-req",
model_name="test-model",
conversation=[],
tokenizer=MagicMock(),
request_metadata=MagicMock(),
)
)
chunks = _parse_sse_chunks(raw_lines)
finish_reasons = [ch["finish_reason"] for c in chunks for ch in c.get("choices", [])]
assert finish_reasons.count("stop") == 1
assert finish_reasons[-1] == "stop"
# The text finish chunk must have finish_reason=None
for idx, c in enumerate(chunks):
for ch in c.get("choices", []):
if c.get("modality") == "text" and ch.get("delta", {}).get("content") == "lo":
assert ch["finish_reason"] is None
@pytest.mark.asyncio
async def test_multi_modal_n2_independent_per_choice():
"""n=2 with text+audio: each choice gets exactly one stop, at the end."""
serving_chat = _build_serving_chat()
request = _make_request(modalities=["text", "audio"], n=2)
async def result_generator():
yield _make_text_omni_output(text="A", token_ids=[10], finish_reason=None, index=0)
yield _make_text_omni_output(text="B", token_ids=[20], finish_reason=None, index=1)
yield _make_text_omni_output(text="", token_ids=[11], finish_reason="stop", index=0)
yield _make_text_omni_output(text="", token_ids=[21], finish_reason="stop", index=1)
yield _make_audio_omni_output(index=0)
yield _make_audio_omni_output(index=1)
raw_lines = await _collect_stream(
serving_chat.chat_completion_stream_generator(
request=request,
result_generator=result_generator(),
request_id="test-req",
model_name="test-model",
conversation=[],
tokenizer=MagicMock(),
request_metadata=MagicMock(),
)
)
chunks = _parse_sse_chunks(raw_lines)
per_choice: dict[int, list] = {}
for c in chunks:
for ch in c.get("choices", []):
per_choice.setdefault(ch["index"], []).append(ch["finish_reason"])
for idx, reasons in per_choice.items():
assert reasons.count("stop") == 1, f"Choice {idx} has {reasons.count('stop')} stops"
assert reasons[-1] == "stop", f"Choice {idx} last reason is {reasons[-1]}"
@pytest.mark.asyncio
async def test_single_modality_audio_only_one_stop():
"""Audio-only streaming: the audio chunk carries finish_reason='stop'."""
serving_chat = _build_serving_chat()
request = _make_request(modalities=["audio"])
async def result_generator():
yield _make_audio_omni_output()
raw_lines = await _collect_stream(
serving_chat.chat_completion_stream_generator(
request=request,
result_generator=result_generator(),
request_id="test-req",
model_name="test-model",
conversation=[],
tokenizer=MagicMock(),
request_metadata=MagicMock(),
)
)
chunks = _parse_sse_chunks(raw_lines)
finish_reasons = [ch["finish_reason"] for c in chunks for ch in c.get("choices", [])]
assert finish_reasons.count("stop") == 1
assert finish_reasons[-1] == "stop"
# ---------------------------------------------------------------------------
# Tests: fallback stop chunk when declared modality is not produced
# ---------------------------------------------------------------------------
@pytest.mark.asyncio
async def test_declared_modality_not_produced_emits_fallback_stop():
"""If request.modalities declares ["text","audio"] but engine only produces
text, a fallback stop chunk is emitted at stream end."""
serving_chat = _build_serving_chat()
request = _make_request(modalities=["text", "audio"])
async def result_generator():
# Engine only produces text, no audio output at all
yield _make_text_omni_output(text="hi", token_ids=[10], finish_reason=None)
yield _make_text_omni_output(text="!", token_ids=[11], finish_reason="stop")
raw_lines = await _collect_stream(
serving_chat.chat_completion_stream_generator(
request=request,
result_generator=result_generator(),
request_id="test-req",
model_name="test-model",
conversation=[],
tokenizer=MagicMock(),
request_metadata=MagicMock(),
)
)
chunks = _parse_sse_chunks(raw_lines)
finish_reasons = [ch["finish_reason"] for c in chunks for ch in c.get("choices", [])]
# Text finish is suppressed (audio not seen yet), but fallback stop
# chunk must appear at end.
assert finish_reasons.count("stop") == 1, f"Expected 1 stop, got {finish_reasons}"
assert finish_reasons[-1] == "stop"
@pytest.mark.asyncio
async def test_declared_modality_not_produced_text_finish_suppressed():
"""When text finishes but audio (declared in modalities) never appears,
the text finish chunk has finish_reason=null (suppressed)."""
serving_chat = _build_serving_chat()
request = _make_request(modalities=["text", "audio"])
async def result_generator():
yield _make_text_omni_output(text="hi", token_ids=[10], finish_reason=None)
yield _make_text_omni_output(text="!", token_ids=[11], finish_reason="stop")
# No audio output — stream ends
raw_lines = await _collect_stream(
serving_chat.chat_completion_stream_generator(
request=request,
result_generator=result_generator(),
request_id="test-req",
model_name="test-model",
conversation=[],
tokenizer=MagicMock(),
request_metadata=MagicMock(),
)
)
chunks = _parse_sse_chunks(raw_lines)
# Find the text finish chunk (content "!")
for c in chunks:
for ch in c.get("choices", []):
if c.get("modality") == "text" and ch.get("delta", {}).get("content") == "!":
# Text finish should be suppressed because audio hasn't appeared
assert ch["finish_reason"] is None
# ---------------------------------------------------------------------------
# Tests: voice/speaker parameter compatibility
# ---------------------------------------------------------------------------
class TestVoiceSpeakerCompat:
"""Tests for voice/speaker parameter handling in chat completions."""
def test_voice_parameter_takes_priority(self):
"""When both voice and speaker are provided via extra_body, voice wins."""
req = ChatCompletionRequest(
model="test-model",
messages=[{"role": "user", "content": "hello"}],
)
# Pydantic model_extra collects unknown fields
req.voice = "alloy" # type: ignore[attr-defined]
req.speaker = "vivian" # type: ignore[attr-defined]
# voice takes priority: getattr(request, "voice", None) returns "alloy"
speaker = getattr(req, "voice", None) or getattr(req, "speaker", None)
assert speaker == "alloy"
def test_speaker_fallback_when_no_voice(self):
"""When only speaker is provided, it is used."""
req = ChatCompletionRequest(
model="test-model",
messages=[{"role": "user", "content": "hello"}],
)
req.speaker = "vivian" # type: ignore[attr-defined]
speaker = getattr(req, "voice", None) or getattr(req, "speaker", None)
assert speaker == "vivian"
def test_neither_voice_nor_speaker(self):
"""When neither is provided, result is None."""
req = ChatCompletionRequest(
model="test-model",
messages=[{"role": "user", "content": "hello"}],
)
speaker = getattr(req, "voice", None) or getattr(req, "speaker", None)
assert speaker is None
def test_empty_voice_falls_back_to_speaker(self):
"""Empty string voice falls back to speaker."""
req = ChatCompletionRequest(
model="test-model",
messages=[{"role": "user", "content": "hello"}],
)
req.voice = "" # type: ignore[attr-defined]
req.speaker = "vivian" # type: ignore[attr-defined]
# Empty string is falsy, so speaker is used
speaker = getattr(req, "voice", None) or getattr(req, "speaker", None)
assert speaker == "vivian"
+55 -4
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@@ -364,10 +364,11 @@ class OmniOpenAIServingChat(OpenAIServingChat, AudioMixin):
if raw_request:
raw_request.state.request_metadata = request_metadata
output_modalities = getattr(request, "modalities", self.engine_client.output_modalities)
request.modalities = (
output_modalities if output_modalities is not None else self.engine_client.output_modalities
)
# Some models will return a list like ["text", None, "audio"], better
# to strip None in the list
engine_output_modalities = [x for x in self.engine_client.output_modalities if x is not None]
output_modalities = getattr(request, "modalities", engine_output_modalities)
request.modalities = output_modalities if output_modalities is not None else engine_output_modalities
num_inference_steps = None
cfg_text_scale = None
@@ -986,6 +987,9 @@ class OmniOpenAIServingChat(OpenAIServingChat, AudioMixin):
num_choices = 1 if request.n is None else request.n
previous_num_tokens = [0] * num_choices
finish_reason_sent = [False] * num_choices
modality_finished: list[set[str]] = [set() for _ in range(num_choices)]
modality_seen: list[set[str]] = [set() for _ in range(num_choices)]
stop_reason_emitted: list[bool] = [False] * num_choices
num_prompt_tokens = 0
num_cached_tokens = None
if self.use_harmony:
@@ -1051,6 +1055,13 @@ class OmniOpenAIServingChat(OpenAIServingChat, AudioMixin):
logger.warning(f"final output type: {final_output_type} is not needed by the request")
continue
# Track which modalities have actually appeared in the stream.
# This is used to determine when all *produced* modalities have
# finished, which may be a subset of request.modalities when the
# engine does not produce every requested modality.
for output in res.outputs:
modality_seen[output.index].add(final_output_type)
if omni_res.metrics:
last_metrics = omni_res.metrics
@@ -1581,6 +1592,16 @@ class OmniOpenAIServingChat(OpenAIServingChat, AudioMixin):
finish_reason_ = "tool_calls"
else:
finish_reason_ = output.finish_reason if output.finish_reason else "stop"
# Only emit finish_reason on the last modality to
# comply with OpenAI streaming spec: exactly one
# chunk per choice carries finish_reason="stop".
modality_finished[i].add("text")
if modality_seen[i] < set(request.modalities) or not all(
m in modality_finished[i] for m in modality_seen[i]
):
finish_reason_ = None
else:
stop_reason_emitted[i] = True
choice_data = ChatCompletionResponseStreamChoice(
index=i,
delta=delta_message,
@@ -1654,6 +1675,17 @@ class OmniOpenAIServingChat(OpenAIServingChat, AudioMixin):
role = self.get_chat_request_role(request)
choices_data = self._create_audio_choice(omni_res, role, request, stream=True)
# Only emit finish_reason on the last modality to
# comply with OpenAI streaming spec.
for choice in choices_data:
if choice.finish_reason is not None:
modality_finished[choice.index].add("audio")
if modality_seen[choice.index] < set(request.modalities) or not all(
m in modality_finished[choice.index] for m in modality_seen[choice.index]
):
choice.finish_reason = None
else:
stop_reason_emitted[choice.index] = True
# Record per-chunk PCM byte count + arrival timestamp for
# audio_underrun_s / audio_continuity_ok_total at finalize.
if req_state is not None and req_state.request_arrival_ts > 0:
@@ -1683,6 +1715,25 @@ class OmniOpenAIServingChat(OpenAIServingChat, AudioMixin):
logger.warning(f"Unsupported streaming final output type: {final_output_type}")
continue
# Fallback: if a choice had modalities finish but no finish_reason="stop"
# was emitted (e.g. request.modalities included a modality the engine
# never produced), emit a final stop chunk for that choice.
for i in range(num_choices):
if modality_finished[i] and not stop_reason_emitted[i]:
stop_choice = ChatCompletionResponseStreamChoice(
index=i,
delta=DeltaMessage(),
finish_reason="stop",
)
stop_chunk = OmniChatCompletionStreamResponse(
id=request_id,
object=chunk_object_type,
created=created_time,
choices=[stop_choice],
model=model_name,
)
data = stop_chunk.model_dump_json(exclude_unset=True)
yield f"data: {data}\n\n"
# Emit audio_underrun_s + audio_continuity_ok_total once per
# request after the audio chunk stream is exhausted. The
# captured reference (req_state_audio_ref) outlives the inner