[v1] EngineArgs for better config handling for v1 (#10382)

Signed-off-by: rickyx <rickyx@anyscale.com>

tests/v1/engine/test_engine_args.py

@@ -0,0 +1,42 @@
+import pytest
+
+from vllm import envs
+from vllm.config import VllmConfig
+from vllm.engine.arg_utils import EngineArgs
+from vllm.usage.usage_lib import UsageContext
+
+if not envs.VLLM_USE_V1:
+    pytest.skip(
+        "Skipping V1 tests. Rerun with `VLLM_USE_V1=1` to test.",
+        allow_module_level=True,
+    )
+
+
+def test_defaults():
+    engine_args = EngineArgs(model="facebook/opt-125m")
+
+    # Assert V1 defaults
+    assert (engine_args.enable_prefix_caching
+            ), "V1 turns on prefix caching by default"
+
+
+def test_defaults_with_usage_context():
+    engine_args = EngineArgs(model="facebook/opt-125m")
+    vllm_config: VllmConfig = engine_args.create_engine_config(
+        UsageContext.LLM_CLASS)
+
+    assert vllm_config.scheduler_config.max_num_seqs == 1024
+    assert vllm_config.scheduler_config.max_num_batched_tokens == 8192
+
+    engine_args = EngineArgs(model="facebook/opt-125m")
+    vllm_config = engine_args.create_engine_config(
+        UsageContext.OPENAI_API_SERVER)
+    assert vllm_config.scheduler_config.max_num_seqs == 1024
+    assert vllm_config.scheduler_config.max_num_batched_tokens == 2048
+
+
+def test_prefix_cache_disabled_with_multimodel():
+    engine_args = EngineArgs(model="llava-hf/llava-1.5-7b-hf")
+
+    vllm_config = engine_args.create_engine_config(UsageContext.LLM_CLASS)
+    assert not vllm_config.cache_config.enable_prefix_caching