[https://nvbugs/6739553][fix] Exempt in-tree venv from sys.path check

tests/test_common/magic_import_hooks.py

@@ -34,6 +34,7 @@
 
 import os
 import sys
+from pathlib import PurePath
 
 import pytest
 
@@ -61,6 +62,12 @@
     "jenkins/scripts/cbts",
 )
 
+# Prefixes of the current installation.
+_INTERPRETER_ROOTS = frozenset(
+    os.path.realpath(prefix)
+    for prefix in (sys.prefix, sys.base_prefix, sys.exec_prefix, sys.base_exec_prefix)
+)
+
 # Debug variable for local runs to skip this check.
 _SKIP_CHECK_ENV = "TRTLLM_SKIP_SYS_PATH_CHECK"
 
@@ -150,6 +157,16 @@ def pytest_runtest_protocol(item, nextitem):
         MagicFinder.purge_magic_sys_modules()
 
 
+def _within(path: str, directory: str) -> bool:
+    """Whether ``path`` is ``directory`` itself or sits below it.
+
+    Compared as whole path components, so a sibling whose name merely starts
+    with the directory's -- ``.venv-3.12-notes`` beside ``.venv-3.12`` -- is not
+    treated as being inside it.
+    """
+    return PurePath(path).is_relative_to(directory)
+
+
 def _project_relative(entry: str) -> str | None:
     """Path of ``entry`` relative to the project root, or None if outside it.
 
@@ -158,7 +175,7 @@ def _project_relative(entry: str) -> str | None:
     """
     root = os.path.realpath(MagicFinder.project_root)
     resolved = os.path.realpath(entry or os.getcwd())
-    if resolved != root and not resolved.startswith(root + os.sep):
+    if not _within(resolved, root):
         return None
     return os.path.relpath(resolved, root)
 
@@ -192,12 +209,25 @@ def _under_exempt_tree(relative: str) -> bool:
     nested path such as a build directory matches its whole tree.
     """
     for tree in _NON_TEST_TREES:
-        prefix = tree.replace("/", os.sep)
-        if relative == prefix or relative.startswith(prefix + os.sep):
+        if _within(relative, tree.replace("/", os.sep)):
             return True
     return False
 
 
+def _under_interpreter_root(resolved: str, project_root: str) -> bool:
+    """Whether an already-resolved path is part of the interpreter's install.
+
+    Other packages may live inside them and add their paths to sys.path,
+    which is not our fault so don't report those paths.
+
+    However, we should still report paths under our project root
+    even if our project root lives inside any of them.
+    """
+    return any(
+        _within(resolved, root) for root in _INTERPRETER_ROOTS if not _within(project_root, root)
+    )
+
+
 def _expected_entries(config) -> set[str]:
     """Project-relative sys.path entries that a run is allowed to contain."""
     expected = {"."}  # the project root itself
@@ -244,7 +274,10 @@ def _check_sys_path(config) -> list[str]:
             continue
         if _under_exempt_tree(relative):
             continue
-        if _is_pytest_basedir(os.path.join(root, relative)):
+        resolved = os.path.join(root, relative)
+        if _under_interpreter_root(resolved, root):
+            continue
+        if _is_pytest_basedir(resolved):
             continue
         if relative not in unexpected:
             unexpected.append(relative)

tests/unittest/others/test_magic_import.py

@@ -25,6 +25,7 @@
 from types import ModuleType, SimpleNamespace
 
 import pytest
+from test_common import magic_import_hooks
 from test_common.magic_import import MagicFinder
 from test_common.magic_import_hooks import (
     _NON_TEST_TREES,
@@ -808,6 +809,57 @@ def test_sys_path_check_matches_exempt_trees_by_path_component(sys_path_report,
     assert sys_path_report(sibling) == [(exempt + "_other").replace("/", os.sep)]
 
 
+@pytest.fixture
+def in_tree_venv(tree, monkeypatch):
+    """Points the interpreter-root exemption at a venv inside the project.
+
+    Patches the resolved roots rather than ``sys.prefix``, which the module
+    reads once at import time.
+    """
+    venv = tree.project_root / ".venv-3.12"
+    site_packages = venv / "lib" / "python3.12" / "site-packages"
+    site_packages.mkdir(parents=True)
+    monkeypatch.setattr(magic_import_hooks, "_INTERPRETER_ROOTS", (str(venv),))
+    return SimpleNamespace(prefix=venv, site_packages=site_packages)
+
+
+def test_sys_path_check_accepts_an_in_tree_virtual_environment(sys_path_report, in_tree_venv):
+    """A venv under the project root is supported layout, not a leak.
+
+    build_wheel.py defaults to ``<project>/.venv-<pyver>``, so a developer who
+    builds that way and then runs pytest from it would otherwise have the
+    interpreter's own library directories reported as if a test file had added
+    them.
+    """
+    vendored = in_tree_venv.site_packages / "some_pkg" / "vendored"
+
+    assert sys_path_report(in_tree_venv.prefix / "bin", vendored) == []
+
+
+def test_sys_path_check_still_reports_a_sibling_of_the_venv(sys_path_report, tree, in_tree_venv):
+    """The venv exemption matches whole components, so a sibling still counts."""
+    sibling = tree.project_root / (in_tree_venv.prefix.name + "-notes")
+    sibling.mkdir(parents=True)
+
+    assert sys_path_report(sibling) == [sibling.name]
+
+
+def test_sys_path_check_ignores_an_interpreter_root_above_the_project(
+    sys_path_report, tree, monkeypatch
+):
+    """A prefix containing the project root must not exempt the whole tree.
+
+    Honouring it would place every entry under the root inside the exemption,
+    so the check would report nothing at all -- sys.base_prefix is ``/usr`` on a
+    system interpreter, which contains a checkout under ``/usr/local``.
+    """
+    helpers = tree.project_root / "tests" / "helpers"
+    helpers.mkdir(parents=True)
+    monkeypatch.setattr(magic_import_hooks, "_INTERPRETER_ROOTS", (str(tree.project_root.parent),))
+
+    assert sys_path_report(helpers) == [os.path.join("tests", "helpers")]
+
+
 def test_sys_path_check_accepts_pythonpath_ini_entries(sys_path_report, tree):
     """pytest.ini's pythonpath is a declared, reviewed entry, not a leak."""
     declared = tree.project_root / "tests" / "declared"