[Build] Add srt_empty extra group for device-agnostic install (#31300)

Co-authored-by: yixiaodapeng <yixiaodapeng@example.com>
Co-authored-by: Alex Nails <alex.nails@radixark.ai>

test/registered/core/test_srt_empty_deps.py

@@ -0,0 +1,91 @@
+# Copyright 2024 SGLang Team
+# Licensed under the Apache License, Version 2.0
+"""Test that runtime_base in pyproject_other.toml remains torch-free.
+
+This prevents accidental introduction of packages that transitively pull
+torch/triton into the srt_empty install target.
+"""
+
+from pathlib import Path
+
+import pytest
+
+from sglang.test.ci.ci_register import register_cpu_ci
+
+register_cpu_ci(est_time=10, suite="base-a-test-cpu")
+
+# Packages known to transitively depend on torch or triton.
+# If a new package is added to runtime_base and it pulls torch,
+# add it here and move it to runtime_common instead.
+TORCH_PULLING_PACKAGES = frozenset(
+    {
+        "torch",
+        "torchao",
+        "timm",
+        "xgrammar",
+        "compressed-tensors",
+        "outlines",
+        "flashinfer",
+        "sgl-kernel",
+    }
+)
+
+
+def _parse_runtime_base() -> set:
+    """Parse runtime_base package names from pyproject_other.toml."""
+    # Try tomllib (3.11+) or tomli
+    try:
+        import tomllib
+    except ModuleNotFoundError:
+        import tomli as tomllib  # type: ignore[no-redef]
+
+    toml_path = Path(__file__).resolve().parents[3] / "python" / "pyproject_other.toml"
+    if not toml_path.exists():
+        pytest.skip(f"pyproject_other.toml not found at {toml_path}")
+
+    with open(toml_path, "rb") as f:
+        data = tomllib.load(f)
+
+    runtime_base = data["project"]["optional-dependencies"]["runtime_base"]
+
+    # Extract bare package names (strip version specifiers and extras)
+    pkg_names = set()
+    for dep in runtime_base:
+        # "package[extra]>=1.0,<2.0" -> "package"
+        name = (
+            dep.split("[")[0]
+            .split(">")[0]
+            .split("<")[0]
+            .split("=")[0]
+            .split("!")[0]
+            .split(";")[0]
+            .strip()
+        )
+        pkg_names.add(name.lower())
+
+    return pkg_names
+
+
+def test_runtime_base_no_torch_deps():
+    """runtime_base must not contain packages that pull in torch."""
+    pkg_names = _parse_runtime_base()
+    violations = pkg_names & TORCH_PULLING_PACKAGES
+    assert not violations, (
+        f"runtime_base contains torch-pulling packages: {sorted(violations)}. "
+        f"Move them to runtime_common to keep srt_empty torch-free."
+    )
+
+
+def test_runtime_base_not_empty():
+    """Sanity check: runtime_base should have a reasonable number of packages."""
+    pkg_names = _parse_runtime_base()
+    assert len(pkg_names) >= 20, (
+        f"runtime_base only has {len(pkg_names)} packages, expected >= 20. "
+        f"Did the toml structure change?"
+    )
+
+
+if __name__ == "__main__":
+    import sys
+
+    sys.exit(pytest.main([__file__, "-v"]))