chore: import upstream snapshot with attribution

tests/test_zen_cpu_platform_detection.py

@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+from unittest.mock import mock_open, patch
+
+from vllm.platforms import _is_amd_zen_cpu
+
+
+def test_is_amd_zen_cpu_detects_amd_with_avx512():
+    cpuinfo = "vendor_id: AuthenticAMD\nflags: avx avx2 avx512f avx512bw"
+    with (
+        patch("os.path.exists", return_value=True),
+        patch("builtins.open", mock_open(read_data=cpuinfo)),
+    ):
+        assert _is_amd_zen_cpu()
+
+
+def test_is_amd_zen_cpu_returns_false_for_amd_without_avx512():
+    cpuinfo = "vendor_id: AuthenticAMD\nflags: avx avx2"
+    with (
+        patch("os.path.exists", return_value=True),
+        patch("builtins.open", mock_open(read_data=cpuinfo)),
+    ):
+        assert not _is_amd_zen_cpu()
+
+
+def test_is_amd_zen_cpu_returns_false_for_intel_with_avx512():
+    cpuinfo = "vendor_id: GenuineIntel\nflags: avx avx2 avx512f"
+    with (
+        patch("os.path.exists", return_value=True),
+        patch("builtins.open", mock_open(read_data=cpuinfo)),
+    ):
+        assert not _is_amd_zen_cpu()
+
+
+def test_is_amd_zen_cpu_returns_false_when_cpuinfo_missing():
+    with patch("os.path.exists", return_value=False):
+        assert not _is_amd_zen_cpu()