[Test] Unify L2/L3 test layout, Buildkite steps, and test helpers (#2556)

Signed-off-by: wangyu <410167048@qq.com>
Signed-off-by: Huang, Zeyu <11222265+fhfuih@users.noreply.github.com>
Signed-off-by: wangyu <53896905+yenuo26@users.noreply.github.com>
Co-authored-by: Huang, Zeyu <11222265+fhfuih@users.noreply.github.com>

tests/model_executor/helpers.py

@@ -0,0 +1,56 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
+"""Shared helpers for ``tests/model_executor``.
+
+:func:`bootstrap_vllm_layer_custom_op_modules` pins vLLM layer modules in
+:data:`sys.modules` before Omni model shims import them.
+
+In isolated ``pytest`` runs (e.g. only ``tests/model_executor/``) different test
+files may pull the same vLLM layer stack in different order.  That can
+re-execute ``@CustomOp.register`` / ``direct_register_custom_op`` and raise
+``Duplicate op name`` for symbols such as ``fatrelu_and_mul``,
+``maybe_calc_kv_scales``, or ``rms_norm``), or
+``RuntimeError`` from :func:`torch.library.Library.define` (e.g.
+``vllm::sequence_parallel_chunk_impl`` from :mod:`vllm.model_executor.models.utils`).
+Eager, idempotent :func:`importlib.import_module` calls for these entrypoints
+make subsequent imports a no-op so registration runs once per process.
+
+``vllm::flashinfer_rotary_embedding`` is registered from
+:mod:`vllm.model_executor.layers.rotary_embedding` (e.g. ``common.ApplyRotaryEmb``).
+In recent vLLM, :mod:`vllm.utils.torch_utils` *also* defines the same op; pre-importing
+``torch_utils`` first and then importing omni (which pulls ``rotary_embedding`` via
+:file:`vllm_omni/patch.py`) runs :func:`torch.library.Library.define` twice and
+raises a duplicate registration error.  Import the rotary package *without* a prior
+dedicated ``torch_utils`` pre-import so a single path owns registration.
+"""
+
+from __future__ import annotations
+
+import importlib
+from typing import Final
+
+# CustomOp- / :func:`direct_register_custom_op` entrypoints.  Do not import
+# ``vllm.model_executor.model_loader`` (that path is part of the duplicate
+# issue for ``MULTIMODAL_REGISTRY._get_model_cls``).
+_VLLM_PREIMPORT_MODULES: Final[tuple[str, ...]] = (
+    "vllm.model_executor.custom_op",
+    # Single registration site for ``vllm::flashinfer_rotary_embedding`` (do not
+    # pre-import ``vllm.utils.torch_utils`` first — it duplicates the op vs. rotary).
+    "vllm.model_executor.layers.rotary_embedding",
+    "vllm.model_executor.layers.activation",
+    "vllm.model_executor.layers.layernorm",  # rms_norm, etc. (Qwen2.5-VL / Omni chain)
+    "vllm.model_executor.layers.conv",
+    "vllm.model_executor.layers.vocab_parallel_embedding",
+    "vllm.model_executor.layers.attention",  # maybe_calc_kv_scales, etc.
+    "vllm.model_executor.models.utils",  # sequence_parallel_chunk_impl, etc. (qwen2_vl import chain)
+)
+
+
+def bootstrap_vllm_layer_custom_op_modules() -> None:
+    """Pre-import vLLM layer and model-util modules that register ops; safe to call multiple times."""
+    for name in _VLLM_PREIMPORT_MODULES:
+        try:
+            importlib.import_module(name)
+        except Exception:
+            # Allow CPU-only or minimal vLLM dev installs: skip if a module is absent.
+            pass