fix(diffusion): convert caller sampling params instead of discarding … (#4115)

Signed-off-by: BruceLoveDecimal <39156883+BruceLoveDecimal@users.noreply.github.com>
Co-authored-by: Gao Han <hgaoaf@connect.ust.hk>

tests/inputs/test_diffusion_sampling_params.py

@@ -0,0 +1,65 @@
+# SPDX-License-Identifier: Apache-2.0
+"""Regression tests for diffusion sampling params coercion."""
+
+from __future__ import annotations
+
+from typing import Any
+
+import pytest
+from vllm.sampling_params import SamplingParams
+
+from vllm_omni.inputs.data import OmniDiffusionSamplingParams
+
+pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
+
+
+def _sampling_params(*, seed: int | None = None, extra_args: dict[str, Any] | None = None) -> SamplingParams:
+    return SamplingParams(max_tokens=1, seed=seed, extra_args=extra_args)
+
+
+def test_from_params_returns_existing_omni_params() -> None:
+    params = OmniDiffusionSamplingParams(num_inference_steps=20)
+
+    converted = OmniDiffusionSamplingParams.from_params(params)
+
+    assert converted is params
+
+
+def test_from_params_converts_sampling_params_seed_and_known_extra_args() -> None:
+    params = _sampling_params(
+        seed=1234,
+        extra_args={
+            "num_inference_steps": 50,
+            "height": 1024,
+            "width": 768,
+            "guidance_scale": 7.5,
+        },
+    )
+
+    converted = OmniDiffusionSamplingParams.from_params(params)
+
+    assert converted.seed == 1234
+    assert converted.num_inference_steps == 50
+    assert converted.height == 1024
+    assert converted.width == 768
+    assert converted.guidance_scale == 7.5
+    assert converted.extra_args == {}
+
+
+def test_from_params_preserves_unknown_extra_args() -> None:
+    params = _sampling_params(
+        extra_args={
+            "height": 512,
+            "pipeline_specific": "kept",
+        },
+    )
+
+    converted = OmniDiffusionSamplingParams.from_params(params)
+
+    assert converted.height == 512
+    assert converted.extra_args == {"pipeline_specific": "kept"}
+
+
+def test_from_params_rejects_unsupported_types() -> None:
+    with pytest.raises(TypeError, match="Diffusion stage requires OmniDiffusionSamplingParams"):
+        OmniDiffusionSamplingParams.from_params({"height": 512})