[Bugfix | Model] Fix SenseNova & Use Well-defined Model Configs (#5877)

Signed-off-by: Alex Brooks <albrooks@redhat.com>

tests/diffusion/models/sensenova_u1/test_sensenova_u1_logits_processor.py

@@ -0,0 +1,72 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""Regression test: SenseNovaU1ForCausalLM instantiation under the diffusion
+config shim must not crash on missing ``head_dtype`` and the resulting
+LogitsProcessor must have ``head_dtype is None`` (= use model dtype)."""
+
+import os
+
+import pytest
+import torch
+from vllm.config import DeviceConfig, VllmConfig, set_current_vllm_config
+from vllm.distributed.parallel_state import (
+    cleanup_dist_env_and_memory,
+    init_distributed_environment,
+    initialize_model_parallel,
+)
+
+from vllm_omni.diffusion.models.sensenova_u1.sensenova_u1_transformer import (
+    SenseNovaU1ForCausalLM,
+)
+from vllm_omni.diffusion.vllm_config import _DiffusionVllmModelConfig
+from vllm_omni.transformers_utils.configs.sensenova_u1 import (
+    SenseNovaU1Config,
+)
+
+pytestmark = [pytest.mark.core_model, pytest.mark.diffusion, pytest.mark.cpu]
+
+
+def _build_tiny_sensenova_u1(quant_config=None, prefix="model"):
+    """Build a minimal SenseNovaU1ForCausalLM for unit tests."""
+    config = SenseNovaU1Config(
+        llm_config={
+            "hidden_size": 64,
+            "num_attention_heads": 2,
+            "num_hidden_layers": 1,
+            "intermediate_size": 128,
+            "vocab_size": 32,
+            "max_position_embeddings": 128,
+            "max_position_embeddings_hw": 128,
+        },
+    )
+    return SenseNovaU1ForCausalLM(config.llm_config, quant_config=quant_config, prefix=prefix)
+
+
+def test_logits_processor_head_dtype_under_diffusion_shim():
+    # Initialize the distributed environment
+    os.environ.setdefault("MASTER_ADDR", "localhost")
+    os.environ.setdefault("MASTER_PORT", "29543")
+    init_distributed_environment(world_size=1, rank=0, local_rank=0, distributed_init_method="env://")
+    initialize_model_parallel()
+
+    # Create a vLLM config with a wrapped diffusion config
+    fake_diff_config = _DiffusionVllmModelConfig(
+        model="sensenova-u1-test",
+        dtype=torch.bfloat16,
+        max_model_len=8192,
+        original_max_model_len=8192,
+    )
+    vllm_config = VllmConfig(
+        device_config=DeviceConfig(device="cpu"),
+    )
+    vllm_config.modelconfig = fake_diff_config  # type: ignore[assignment]
+
+    # Build a tiny version of the Causal LM component
+    with set_current_vllm_config(vllm_config):
+        model = _build_tiny_sensenova_u1()
+
+    # Ensure that we have a set head_dtype attribute. Currently, the head_dtype
+    # is set to None
+    head_dtype = model.logits_processor.head_dtype
+    assert head_dtype is None
+    cleanup_dist_env_and_memory()