[Hardware] Support platforms and plugin system (#774)

Signed-off-by: gcanlin <canlinguosdu@gmail.com>

tests/entrypoints/test_stage_utils.py

@@ -1,5 +1,6 @@
 import os
 import sys
+from unittest.mock import MagicMock
 
 import pytest
 
@@ -42,6 +43,14 @@ def _make_dummy_torch(call_log):
     return _Torch
 
 
+def _make_mock_platform(device_type: str = "cuda", env_var: str = "CUDA_VISIBLE_DEVICES"):
+    """Create a mock platform for testing."""
+    mock_platform = MagicMock()
+    mock_platform.device_type = device_type
+    mock_platform.device_control_env_var = env_var
+    return mock_platform
+
+
 @pytest.mark.usefixtures("clean_gpu_memory_between_tests")
 def test_set_stage_devices_respects_logical_ids(monkeypatch):
     # Preserve an existing logical mapping and ensure devices "0,1" map through it.
@@ -49,9 +58,51 @@ def test_set_stage_devices_respects_logical_ids(monkeypatch):
     call_log: list[int] = []
     dummy_torch = _make_dummy_torch(call_log)
     monkeypatch.setitem(sys.modules, "torch", dummy_torch)
-    monkeypatch.setattr("vllm_omni.utils.detect_device_type", lambda: "cuda")
-    monkeypatch.setattr("vllm_omni.utils.get_device_control_env_var", lambda: "CUDA_VISIBLE_DEVICES")
+
+    # Mock the platform at the source module where it's defined
+    mock_platform = _make_mock_platform(device_type="cuda", env_var="CUDA_VISIBLE_DEVICES")
+    monkeypatch.setattr(
+        "vllm_omni.platforms.current_omni_platform",
+        mock_platform,
+    )
 
     set_stage_devices(stage_id=0, devices="0,1")
 
     assert os.environ["CUDA_VISIBLE_DEVICES"] == "6,7"
+
+
+@pytest.mark.usefixtures("clean_gpu_memory_between_tests")
+def test_set_stage_devices_npu_platform(monkeypatch):
+    """Test that set_stage_devices works correctly for NPU platform."""
+    monkeypatch.setenv("ASCEND_RT_VISIBLE_DEVICES", "4,5")
+    call_log: list[int] = []
+
+    # Create NPU mock torch
+    class _Npu:
+        @staticmethod
+        def is_available():
+            return True
+
+        @staticmethod
+        def set_device(idx):
+            call_log.append(idx)
+
+        @staticmethod
+        def device_count():
+            return 2
+
+    class _NpuTorch:
+        npu = _Npu
+
+    monkeypatch.setitem(sys.modules, "torch", _NpuTorch)
+
+    # Mock NPU platform at the source module where it's defined
+    mock_platform = _make_mock_platform(device_type="npu", env_var="ASCEND_RT_VISIBLE_DEVICES")
+    monkeypatch.setattr(
+        "vllm_omni.platforms.current_omni_platform",
+        mock_platform,
+    )
+
+    set_stage_devices(stage_id=0, devices="0,1")
+
+    assert os.environ["ASCEND_RT_VISIBLE_DEVICES"] == "4,5"