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

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

tests/entrypoints/test_launch_cli.py

@@ -0,0 +1,111 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""Unit tests for the `vllm launch` CLI subcommand."""
+
+import argparse
+from unittest.mock import patch
+
+import pytest
+
+from vllm.entrypoints.cli.launch import (
+    LaunchSubcommand,
+    RenderSubcommand,
+    cmd_init,
+)
+from vllm.utils.argparse_utils import FlexibleArgumentParser
+
+
+@pytest.fixture
+def launch_parser():
+    parser = FlexibleArgumentParser(description="test")
+    subparsers = parser.add_subparsers(required=False, dest="subparser")
+    LaunchSubcommand().subparser_init(subparsers)
+    return parser
+
+
+def test_subcommand_name():
+    assert LaunchSubcommand().name == "launch"
+
+
+def test_cmd_init_returns_subcommand():
+    result = cmd_init()
+    assert len(result) == 1
+    assert isinstance(result[0], LaunchSubcommand)
+
+
+# -- Parsing: `vllm launch render` --
+
+
+def test_parse_launch_render(launch_parser):
+    args = launch_parser.parse_args(["launch", "render", "--model", "test-model"])
+    assert args.launch_component == "render"
+
+
+def test_parse_launch_requires_component(launch_parser):
+    with pytest.raises(SystemExit):
+        launch_parser.parse_args(["launch", "--model", "test-model"])
+
+
+def test_parse_launch_invalid_component(launch_parser):
+    with pytest.raises(SystemExit):
+        launch_parser.parse_args(["launch", "unknown", "--model", "test-model"])
+
+
+# -- Dispatch --
+
+
+def test_cmd_launch_render_calls_run():
+    args = argparse.Namespace(model_tag=None, model="test-model")
+    with patch("vllm.entrypoints.cli.launch.uvloop.run") as mock_uvloop_run:
+        RenderSubcommand.cmd(args)
+        mock_uvloop_run.assert_called_once()
+
+
+def test_cmd_launch_model_tag_overrides():
+    args = argparse.Namespace(
+        model_tag="tag-model",
+        model="original-model",
+        launch_command=lambda a: None,
+    )
+    LaunchSubcommand.cmd(args)
+    assert args.model == "tag-model"
+
+
+def test_cmd_launch_model_tag_none():
+    args = argparse.Namespace(
+        model_tag=None,
+        model="original-model",
+        launch_command=lambda a: None,
+    )
+    LaunchSubcommand.cmd(args)
+    assert args.model == "original-model"
+
+
+def test_cmd_dispatches():
+    called = {}
+
+    def fake_dispatch(args):
+        called["args"] = args
+
+    args = argparse.Namespace(launch_command=fake_dispatch)
+    LaunchSubcommand.cmd(args)
+    assert "args" in called
+
+
+# -- Module registration --
+
+
+def test_subparser_init_returns_parser():
+    parser = FlexibleArgumentParser(description="test")
+    subparsers = parser.add_subparsers(required=False, dest="subparser")
+    result = LaunchSubcommand().subparser_init(subparsers)
+    assert isinstance(result, FlexibleArgumentParser)
+
+
+def test_launch_registered_in_main():
+    """Verify that launch module is importable as a CLI module."""
+    import vllm.entrypoints.cli.launch as launch_module
+
+    assert hasattr(launch_module, "cmd_init")
+    subcmds = launch_module.cmd_init()
+    assert any(s.name == "launch" for s in subcmds)