[Frontend] Change CompilationMode to a proper Enum (#28165)

Signed-off-by: Yanan Cao <gmagogsfm@gmail.com>

tests/utils_/test_argparse_utils.py

@@ -8,6 +8,7 @@ import os
 import pytest
 import yaml
 from transformers import AutoTokenizer
+from pydantic import ValidationError
 
 from vllm.transformers_utils.detokenizer_utils import convert_ids_list_to_tokens
 
@@ -376,6 +377,65 @@ def test_load_config_file(tmp_path):
     os.remove(str(config_file_path))
 
 
+def test_compilation_mode_string_values(parser):
+    """Test that -O.mode accepts both integer and string mode values."""
+    args = parser.parse_args(["-O.mode", "0"])
+    assert args.compilation_config == {"mode": 0}
+
+    args = parser.parse_args(["-O3"])
+    assert args.compilation_config == {"mode": 3}
+
+    args = parser.parse_args(["-O.mode=NONE"])
+    assert args.compilation_config == {"mode": "NONE"}
+
+    args = parser.parse_args(["-O.mode", "STOCK_TORCH_COMPILE"])
+    assert args.compilation_config == {"mode": "STOCK_TORCH_COMPILE"}
+
+    args = parser.parse_args(["-O.mode=DYNAMO_TRACE_ONCE"])
+    assert args.compilation_config == {"mode": "DYNAMO_TRACE_ONCE"}
+
+    args = parser.parse_args(["-O.mode", "VLLM_COMPILE"])
+    assert args.compilation_config == {"mode": "VLLM_COMPILE"}
+
+    args = parser.parse_args(["-O.mode=none"])
+    assert args.compilation_config == {"mode": "none"}
+
+    args = parser.parse_args(["-O.mode=vllm_compile"])
+    assert args.compilation_config == {"mode": "vllm_compile"}
+
+
+def test_compilation_config_mode_validator():
+    """Test that CompilationConfig.mode field validator converts strings to integers."""
+    from vllm.config.compilation import CompilationConfig, CompilationMode
+
+    config = CompilationConfig(mode=0)
+    assert config.mode == CompilationMode.NONE
+
+    config = CompilationConfig(mode=3)
+    assert config.mode == CompilationMode.VLLM_COMPILE
+
+    config = CompilationConfig(mode="NONE")
+    assert config.mode == CompilationMode.NONE
+
+    config = CompilationConfig(mode="STOCK_TORCH_COMPILE")
+    assert config.mode == CompilationMode.STOCK_TORCH_COMPILE
+
+    config = CompilationConfig(mode="DYNAMO_TRACE_ONCE")
+    assert config.mode == CompilationMode.DYNAMO_TRACE_ONCE
+
+    config = CompilationConfig(mode="VLLM_COMPILE")
+    assert config.mode == CompilationMode.VLLM_COMPILE
+
+    config = CompilationConfig(mode="none")
+    assert config.mode == CompilationMode.NONE
+
+    config = CompilationConfig(mode="vllm_compile")
+    assert config.mode == CompilationMode.VLLM_COMPILE
+
+    with pytest.raises(ValidationError, match="Invalid compilation mode"):
+        CompilationConfig(mode="INVALID_MODE")
+
+
 def test_flat_product():
     # Check regular itertools.product behavior
     result1 = list(flat_product([1, 2, 3], ["a", "b"]))