[Test] Add regression test for MiniCPM-o 4.5 audio-stream output kinds (#5356)

Signed-off-by: Inesh Reddy <ineshreddy249@gmail.com>

tests/entrypoints/openai_api/test_serving_chat_minicpmo45_stream_output_kinds.py

@@ -0,0 +1,77 @@
+# SPDX-License-Identifier: Apache-2.0
+"""Regression tests for MiniCPM-o 4.5 audio-streaming output-kind coercion.
+
+Chat ``stream=true`` coerces every AR stage to DELTA. For MiniCPM-o 4.5 that
+hands ``llm2tts`` one thinker token per step while the forwarded hidden states
+still span prompt + generated, so the talker is conditioned on a broadcast
+mismatch (issue #5298). The thinker must stay FINAL_ONLY; only the talker
+streams.
+"""
+
+from __future__ import annotations
+
+from types import SimpleNamespace
+
+import pytest
+from vllm.sampling_params import RequestOutputKind, SamplingParams
+
+pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
+
+MINICPMO45_ARCH = "MiniCPMO45OmniForConditionalGeneration"
+
+
+@pytest.fixture
+def serving_chat():
+    from vllm_omni.entrypoints.openai.serving_chat import OmniOpenAIServingChat
+
+    return object.__new__(OmniOpenAIServingChat)
+
+
+def _stage(model_arch: str, model_stage: str) -> SimpleNamespace:
+    # SimpleNamespace, not MagicMock: _stage_get prefers .get() when present,
+    # and a MagicMock satisfies hasattr(obj, "get") and returns a mock.
+    return SimpleNamespace(engine_args=SimpleNamespace(model_arch=model_arch, model_stage=model_stage))
+
+
+def _minicpmo45_stages():
+    return [_stage(MINICPMO45_ARCH, "llm"), _stage(MINICPMO45_ARCH, "tts")]
+
+
+def _delta_params(n: int = 2):
+    return [SamplingParams(output_kind=RequestOutputKind.DELTA) for _ in range(n)]
+
+
+def test_thinker_forced_final_only_talker_stays_delta(serving_chat):
+    serving_chat.engine_client = SimpleNamespace(stage_configs=_minicpmo45_stages())
+
+    out = serving_chat._fix_minicpmo45_audio_stream_output_kinds(_delta_params(), ["text", "audio"])
+
+    assert out[0].output_kind is RequestOutputKind.FINAL_ONLY
+    assert out[1].output_kind is RequestOutputKind.DELTA
+
+
+@pytest.mark.parametrize("modalities", [None, [], ["text"]])
+def test_non_audio_request_is_untouched(serving_chat, modalities):
+    serving_chat.engine_client = SimpleNamespace(stage_configs=_minicpmo45_stages())
+
+    out = serving_chat._fix_minicpmo45_audio_stream_output_kinds(_delta_params(), modalities)
+
+    assert [p.output_kind for p in out] == [RequestOutputKind.DELTA] * 2
+
+
+def test_other_architectures_are_untouched(serving_chat):
+    stages = [_stage("SomeOtherOmniForConditionalGeneration", "llm")]
+    serving_chat.engine_client = SimpleNamespace(stage_configs=stages)
+
+    out = serving_chat._fix_minicpmo45_audio_stream_output_kinds(_delta_params(1), ["text", "audio"])
+
+    assert out[0].output_kind is RequestOutputKind.DELTA
+
+
+def test_shorter_sampling_params_list_does_not_raise(serving_chat):
+    serving_chat.engine_client = SimpleNamespace(stage_configs=_minicpmo45_stages())
+
+    out = serving_chat._fix_minicpmo45_audio_stream_output_kinds(_delta_params(1), ["text", "audio"])
+
+    assert len(out) == 1
+    assert out[0].output_kind is RequestOutputKind.FINAL_ONLY