Add test_linker_warnings.py

As generated by ChatGPT 5, with minor manual tweaks.

Author: rwgk

cuda_core/tests/test_linker_warnings.py

@@ -0,0 +1,187 @@
+# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: LicenseRef-NVIDIA-SOFTWARE-LICENSE
+
+import builtins
+import sys
+import types
+import warnings
+
+import pytest
+from cuda.core.experimental import _linker as linker
+
+
+@pytest.fixture(autouse=True)
+def fresh_env(monkeypatch):
+    """
+    Put the module under test into a predictable state:
+      - neutralize global caches,
+      - provide a minimal 'driver' object,
+      - make 'handle_return' a passthrough,
+      - stabilize platform for deterministic messages.
+    """
+
+    class FakeDriver:
+        # Something realistic but not used by the logic under test
+        def cuDriverGetVersion(self):
+            return 12090
+
+    monkeypatch.setattr(linker, "_driver", None, raising=False)
+    monkeypatch.setattr(linker, "_nvjitlink", None, raising=False)
+    monkeypatch.setattr(linker, "_driver_ver", None, raising=False)
+    monkeypatch.setattr(linker, "driver", FakeDriver(), raising=False)
+    monkeypatch.setattr(linker, "handle_return", lambda x: x, raising=False)
+
+    # Normalize platform-dependent wording (if any)
+    monkeypatch.setattr(sys, "platform", "linux", raising=False)
+
+    # Ensure a clean sys.modules slate for our synthetic packages
+    for modname in list(sys.modules):
+        if modname.startswith("cuda.bindings.nvjitlink") or modname == "cuda.bindings" or modname == "cuda":
+            sys.modules.pop(modname, None)
+
+    yield
+
+    # Cleanup any stubs we added
+    for modname in list(sys.modules):
+        if modname.startswith("cuda.bindings.nvjitlink") or modname == "cuda.bindings" or modname == "cuda":
+            sys.modules.pop(modname, None)
+
+
+def _install_public_nvjitlink_stub():
+    """
+    Provide enough structure so that:
+      - `from cuda.bindings import nvjitlink` succeeds
+      - `from cuda.bindings._internal import nvjitlink as inner_nvjitlink` succeeds
+    We don't care about the contents of inner_nvjitlink because tests stub
+    `_nvjitlink_has_version_symbol()` directly.
+    """
+    # Make 'cuda' a package
+    cuda_pkg = sys.modules.get("cuda") or types.ModuleType("cuda")
+    cuda_pkg.__path__ = []  # mark as package
+    sys.modules["cuda"] = cuda_pkg
+
+    # Make 'cuda.bindings' a package
+    bindings_pkg = sys.modules.get("cuda.bindings") or types.ModuleType("cuda.bindings")
+    bindings_pkg.__path__ = []  # mark as package
+    sys.modules["cuda.bindings"] = bindings_pkg
+
+    # Public-facing nvjitlink module
+    sys.modules["cuda.bindings.nvjitlink"] = types.ModuleType("cuda.bindings.nvjitlink")
+
+    # Make 'cuda.bindings._internal' a package
+    internal_pkg = sys.modules.get("cuda.bindings._internal") or types.ModuleType("cuda.bindings._internal")
+    internal_pkg.__path__ = []  # mark as package
+    sys.modules["cuda.bindings._internal"] = internal_pkg
+
+    # Dummy inner nvjitlink module (imported but not actually used by tests)
+    inner_nvjitlink_mod = types.ModuleType("cuda.bindings._internal.nvjitlink")
+    # (optional) a no-op placeholder so attributes exist if accessed accidentally
+    inner_nvjitlink_mod._inspect_function_pointer = lambda *_args, **_kw: True
+    sys.modules["cuda.bindings._internal.nvjitlink"] = inner_nvjitlink_mod
+
+
+def _collect_runtime_warnings(record):
+    return [w for w in record if issubclass(w.category, RuntimeWarning)]
+
+
+def _block_nvjitlink_import(monkeypatch):
+    """Force 'from cuda.bindings import nvjitlink' to fail, regardless of sys.path."""
+    real_import = builtins.__import__
+
+    def fake_import(name, globals=None, locals=None, fromlist=(), level=0):
+        # Handle both 'from cuda.bindings import nvjitlink' and direct submodule imports
+        target = "cuda.bindings.nvjitlink"
+        if name == target or (name == "cuda.bindings" and fromlist and "nvjitlink" in fromlist):
+            raise ModuleNotFoundError(target)
+        return real_import(name, globals, locals, fromlist, level)
+
+    monkeypatch.setattr(builtins, "__import__", fake_import)
+
+
+def test_warns_when_python_nvjitlink_missing(monkeypatch):
+    """
+    Case 1: 'from cuda.bindings import nvjitlink' fails -> bindings missing.
+    Expect a RuntimeWarning stating that cuda.bindings.nvjitlink is not available,
+    and that we fall back to cuLink* (function returns True).
+    """
+    # Ensure nothing is preloaded and actively block future imports.
+    sys.modules.pop("cuda.bindings.nvjitlink", None)
+    sys.modules.pop("cuda.bindings", None)
+    sys.modules.pop("cuda", None)
+    _block_nvjitlink_import(monkeypatch)
+
+    with warnings.catch_warnings(record=True) as rec:
+        warnings.simplefilter("always")
+        ret = linker._decide_nvjitlink_or_driver()
+
+    assert ret is True
+    warns = _collect_runtime_warnings(rec)
+    assert len(warns) == 1
+    msg = str(warns[0].message)
+    assert "cuda.bindings.nvjitlink is not available" in msg
+    assert "the culink APIs will be used instead" in msg
+    assert "recent version of cuda-bindings." in msg
+
+
+def test_warns_when_nvjitlink_symbol_probe_raises(monkeypatch):
+    """
+    Case 2: Bindings present, but symbol probe raises RuntimeError -> 'not available'.
+    Expect a RuntimeWarning mentioning 'libnvJitLink.so* is not available' and fallback.
+    """
+    _install_public_nvjitlink_stub()
+
+    def raising_probe(_inner):
+        raise RuntimeError("simulated: nvJitLink symbol unavailable")
+
+    monkeypatch.setattr(linker, "_nvjitlink_has_version_symbol", raising_probe, raising=True)
+
+    with warnings.catch_warnings(record=True) as rec:
+        warnings.simplefilter("always")
+        ret = linker._decide_nvjitlink_or_driver()
+
+    assert ret is True
+    warns = _collect_runtime_warnings(rec)
+    assert len(warns) == 1
+    msg = str(warns[0].message)
+    assert "libnvJitLink.so* is not available" in msg
+    assert "cuda.bindings.nvjitlink is not usable" in msg
+    assert "the culink APIs will be used instead" in msg
+    assert "recent version of nvJitLink." in msg
+
+
+def test_warns_when_nvjitlink_too_old(monkeypatch):
+    """
+    Case 3: Bindings present, probe returns False -> 'too old (<12.3)'.
+    Expect a RuntimeWarning mentioning 'too old (<12.3)' and fallback.
+    """
+    _install_public_nvjitlink_stub()
+    monkeypatch.setattr(linker, "_nvjitlink_has_version_symbol", lambda _inner: False, raising=True)
+
+    with warnings.catch_warnings(record=True) as rec:
+        warnings.simplefilter("always")
+        ret = linker._decide_nvjitlink_or_driver()
+
+    assert ret is True
+    warns = _collect_runtime_warnings(rec)
+    assert len(warns) == 1
+    msg = str(warns[0].message)
+    assert "libnvJitLink.so* is too old (<12.3)" in msg
+    assert "cuda.bindings.nvjitlink is not usable" in msg
+    assert "the culink APIs will be used instead" in msg
+    assert "recent version of nvJitLink." in msg
+
+
+def test_uses_nvjitlink_when_available_and_ok(monkeypatch):
+    """
+    Sanity: Bindings present and probe returns True → no warning, use nvJitLink.
+    """
+    _install_public_nvjitlink_stub()
+    monkeypatch.setattr(linker, "_nvjitlink_has_version_symbol", lambda _inner: True, raising=True)
+
+    with warnings.catch_warnings(record=True) as rec:
+        warnings.simplefilter("always")
+        ret = linker._decide_nvjitlink_or_driver()
+
+    assert ret is False  # do NOT fall back
+    warns = _collect_runtime_warnings(rec)
+    assert not warns