[Frontend] Add vllm launch command for GPU-less preprocessing serving (#34551)

Signed-off-by: HyunKyun Moon <mhg5303@gmail.com>

tests/entrypoints/openai/cpu/test_render.py

@@ -0,0 +1,226 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+"""Tests for the /render endpoints that expose prompt preprocessing."""
+
+import httpx
+import pytest
+import pytest_asyncio
+
+from tests.utils import RemoteOpenAIServer
+
+MODEL_NAME = "hmellor/tiny-random-LlamaForCausalLM"
+
+
+@pytest.fixture(scope="module")
+def server():
+    args: list[str] = []
+
+    with RemoteOpenAIServer(MODEL_NAME, args) as remote_server:
+        yield remote_server
+
+
+@pytest_asyncio.fixture
+async def client(server):
+    async with httpx.AsyncClient(
+        base_url=server.url_for(""), timeout=30.0
+    ) as http_client:
+        yield http_client
+
+
+@pytest.mark.asyncio
+async def test_completion_render_basic(client):
+    """Test basic completion render endpoint."""
+    # Make request to render endpoint
+    response = await client.post(
+        "/v1/completions/render",
+        json={
+            "model": MODEL_NAME,
+            "prompt": "When should a chat-completions handler return an empty string?",
+        },
+    )
+
+    assert response.status_code == 200
+    data = response.json()
+
+    # Verify response structure
+    assert isinstance(data, list)
+    assert len(data) > 0
+
+    # Verify first prompt
+    first_prompt = data[0]
+    assert "prompt_token_ids" in first_prompt
+    assert "prompt" in first_prompt
+    assert isinstance(first_prompt["prompt_token_ids"], list)
+    assert len(first_prompt["prompt_token_ids"]) > 0
+    assert isinstance(first_prompt["prompt"], str)
+
+    # Verify prompt text is preserved
+    assert (
+        "When should a chat-completions handler return an empty string?"
+        in first_prompt["prompt"]
+    )
+
+
+@pytest.mark.asyncio
+async def test_chat_completion_render_basic(client):
+    """Test basic chat completion render endpoint."""
+    # Make request to render endpoint
+    response = await client.post(
+        "/v1/chat/completions/render",
+        json={
+            "model": MODEL_NAME,
+            "messages": [
+                {
+                    "role": "user",
+                    "content": (
+                        "Returning an empty string for the prompt may be confusing."
+                    ),
+                }
+            ],
+        },
+    )
+
+    assert response.status_code == 200
+    data = response.json()
+
+    # Verify response structure - should be [conversation, engine_prompts]
+    assert isinstance(data, list)
+    assert len(data) == 2
+
+    conversation, engine_prompts = data
+
+    # Verify conversation
+    assert isinstance(conversation, list)
+    assert len(conversation) > 0
+    assert conversation[0]["role"] == "user"
+    assert "empty string" in conversation[0]["content"]
+
+    # Verify engine_prompts
+    assert isinstance(engine_prompts, list)
+    assert len(engine_prompts) > 0
+
+    first_prompt = engine_prompts[0]
+    assert "prompt_token_ids" in first_prompt
+    assert "prompt" in first_prompt
+    assert isinstance(first_prompt["prompt_token_ids"], list)
+    assert len(first_prompt["prompt_token_ids"]) > 0
+
+    # Verify chat template was applied (should have instruction markers)
+    assert "[INST]" in first_prompt["prompt"]
+    assert "[/INST]" in first_prompt["prompt"]
+
+    # Verify token IDs are correctly preserved as integers
+    token_ids = first_prompt["prompt_token_ids"]
+    assert all(isinstance(tid, int) for tid in token_ids)
+    # Verify BOS token (usually 1 for LLaMA models)
+    assert token_ids[0] == 1
+
+
+@pytest.mark.asyncio
+async def test_completion_render_multiple_prompts(client):
+    """Test completion render with multiple prompts."""
+    response = await client.post(
+        "/v1/completions/render",
+        json={
+            "model": MODEL_NAME,
+            "prompt": ["Hello world", "Goodbye world"],
+        },
+    )
+
+    assert response.status_code == 200
+    data = response.json()
+
+    # Should return two prompts
+    assert isinstance(data, list)
+    assert len(data) == 2
+
+    # Verify both prompts have required fields
+    for prompt in data:
+        assert "prompt_token_ids" in prompt
+        assert "prompt" in prompt
+        assert len(prompt["prompt_token_ids"]) > 0
+
+
+@pytest.mark.asyncio
+async def test_chat_completion_render_multi_turn(client):
+    """Test chat completion render with multi-turn conversation."""
+    response = await client.post(
+        "/v1/chat/completions/render",
+        json={
+            "model": MODEL_NAME,
+            "messages": [
+                {"role": "user", "content": "Hello"},
+                {"role": "assistant", "content": "Hi there!"},
+                {"role": "user", "content": "How are you?"},
+            ],
+        },
+    )
+
+    assert response.status_code == 200
+    data = response.json()
+
+    conversation, engine_prompts = data
+
+    # Verify all messages preserved
+    assert len(conversation) == 3
+    assert conversation[0]["role"] == "user"
+    assert conversation[1]["role"] == "assistant"
+    assert conversation[2]["role"] == "user"
+
+    # Verify tokenization occurred
+    assert len(engine_prompts) > 0
+    assert len(engine_prompts[0]["prompt_token_ids"]) > 0
+
+
+@pytest.mark.asyncio
+async def test_completion_render_error_invalid_model(client):
+    """Test completion render with invalid model returns error."""
+    response = await client.post(
+        "/v1/completions/render",
+        json={
+            "model": "invalid-model-name",
+            "prompt": "Hello",
+        },
+    )
+
+    assert response.status_code == 404
+    data = response.json()
+    assert "error" in data
+
+
+@pytest.mark.asyncio
+async def test_chat_completion_render_error_invalid_model(client):
+    """Test chat completion render with invalid model returns error."""
+    response = await client.post(
+        "/v1/chat/completions/render",
+        json={
+            "model": "invalid-model-name",
+            "messages": [{"role": "user", "content": "Hello"}],
+        },
+    )
+
+    assert response.status_code == 404
+    data = response.json()
+    assert "error" in data
+
+
+@pytest.mark.asyncio
+async def test_completion_render_no_generation(client):
+    """Verify render endpoint does not generate text."""
+    # This test verifies that calling render is fast (no generation)
+    import time
+
+    start = time.perf_counter()
+    response = await client.post(
+        "/v1/completions/render",
+        json={
+            "model": MODEL_NAME,
+            "prompt": "Tell me a very long story about " * 10,
+        },
+    )
+    elapsed = time.perf_counter() - start
+
+    assert response.status_code == 200
+    # Render should be fast (< 1 second) since no generation
+    assert elapsed < 1.0