learningcircuit--local-deep-research/tests/hooks/test_check_pathlib_usage.py

"""
Tests for the check-pathlib-usage pre-commit hook.

Covers the alias-bypass regression: ``import os as <alias>`` followed by
``<alias>.path.*`` used to slip past the AST matcher because it only
looked for the literal name ``os``. That is how a ``_os.path.join(...)``
landed in #4880 and had to be caught by human review.
"""

import subprocess
import sys
import tempfile
from pathlib import Path


HOOK_SCRIPT = (
    Path(__file__).parent.parent.parent
    / ".pre-commit-hooks"
    / "check-pathlib-usage.py"
)


def _run_hook(
    content: str, filename: str = "service.py"
) -> subprocess.CompletedProcess:
    with tempfile.TemporaryDirectory() as d:
        path = Path(d) / filename
        path.parent.mkdir(parents=True, exist_ok=True)
        path.write_text(content)
        return subprocess.run(
            [sys.executable, str(HOOK_SCRIPT), str(path)],
            capture_output=True,
            text=True,
        )


class TestPlainOsPath:
    """Regression guards: the pre-existing ``os.path.*`` detection still works."""

    def test_plain_os_path_join_is_caught(self):
        result = _run_hook("import os\nx = os.path.join('a', 'b')\n")
        assert result.returncode == 1
        assert "os.path.join" in result.stdout

    def test_from_os_import_path_is_caught(self):
        result = _run_hook("from os import path\n")
        assert result.returncode == 1
        assert "from os import path" in result.stdout

    def test_from_os_path_import_join_is_caught(self):
        result = _run_hook("from os.path import join\n")
        assert result.returncode == 1
        assert "from os.path import join" in result.stdout

    def test_expandvars_is_allowed(self):
        """os.path.expandvars has no pathlib equivalent and must not be flagged."""
        result = _run_hook("import os\nx = os.path.expandvars('$HOME')\n")
        assert result.returncode == 0


class TestAliasedOsImport:
    """The bug: ``import os as <alias>`` used to bypass the matcher."""

    def test_aliased_os_path_join_is_caught(self):
        """The exact pattern that slipped into #4880."""
        result = _run_hook("import os as _os\nx = _os.path.join('a', 'b')\n")
        assert result.returncode == 1
        assert "os.path.join" in result.stdout

    def test_aliased_os_path_exists_is_caught(self):
        result = _run_hook(
            "import os as os_module\n"
            "if os_module.path.exists('/x'):\n"
            "    pass\n"
        )
        assert result.returncode == 1
        assert "os.path.exists" in result.stdout

    def test_aliased_expandvars_is_allowed(self):
        """Alias bypass must not extend the expandvars carve-out to new code
        — but expandvars itself stays allowed regardless of how os is bound."""
        result = _run_hook(
            "import os as _os\nx = _os.path.expandvars('$HOME')\n"
        )
        assert result.returncode == 0

    def test_multiple_aliases_in_one_import(self):
        """``import os, sys`` style — os is still tracked."""
        result = _run_hook("import os, sys\nx = os.path.join('a', 'b')\n")
        assert result.returncode == 1
        assert "os.path.join" in result.stdout


class TestNoFalsePositives:
    """Aliased ``os`` imports that do NOT touch ``.path`` must stay silent."""

    def test_aliased_os_chmod_only(self):
        result = _run_hook("import os as _os\n_os.chmod('/tmp/x', 0o644)\n")
        assert result.returncode == 0

    def test_aliased_os_environ_only(self):
        result = _run_hook(
            "import os as os_module\nci = os_module.environ.get('CI')\n"
        )
        assert result.returncode == 0

    def test_clean_pathlib_code(self):
        result = _run_hook("from pathlib import Path\np = Path('a') / 'b'\n")
        assert result.returncode == 0

    def test_no_os_import_at_all(self):
        result = _run_hook("x = 'hello'\nprint(x)\n")
        assert result.returncode == 0


class TestAllowedFilesBypass:
    """The ALLOWED_FILES list in the hook must still suppress violations
    for the legacy exceptions."""

    def test_log_utils_is_exempt(self):
        result = _run_hook(
            "import os\nx = os.path.join('a', 'b')\n",
            filename="src/local_deep_research/utilities/log_utils.py",
        )
        assert result.returncode == 0

    def test_paths_config_is_exempt(self):
        result = _run_hook(
            "import os\nx = os.path.join('a', 'b')\n",
            filename="src/local_deep_research/config/paths.py",
        )
        assert result.returncode == 0