[diffusion][feature] Add component-selective offload policies (#5929)

Signed-off-by: lishunyang12 <lishunyang12@163.com>

tests/diffusion/offloader/conftest.py

@@ -0,0 +1,26 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
+
+"""Shared runtime fixtures for diffusion offloader tests."""
+
+import gc
+
+import pytest
+import torch.distributed as dist
+
+from tests.helpers.runtime import get_distributed_init_method
+from vllm_omni.platforms import current_omni_platform
+
+
+@pytest.fixture(scope="module")
+def dist_group():
+    dist.init_process_group("gloo", rank=0, world_size=1, init_method=get_distributed_init_method())
+    try:
+        yield
+    finally:
+        if dist.is_initialized():
+            dist.destroy_process_group()
+        gc.collect()
+        if current_omni_platform.is_available():
+            current_omni_platform.empty_cache()
+            current_omni_platform.synchronize()