"""pathguard cells, standard library only.

Q149 (2026-11-01): this module imported `pytest` and used it for
`pytest.raises` alone.  The interpreter `beam/CHECK` resolves has no pytest --
Q128 moved the lane's four other pytest-only files onto `beam_assert` for
exactly that reason -- so the import failed and `run_lane_tests.py` reported
all eight cells as one `IMPORT-FAIL test_pathguard.py` line: eight cells graded
nothing, and the lane gate was red with a message that reads like a missing
library rather than a broken one.  The fix is the lane's existing shim, not a
new idiom: `beam_assert.raises` is the `pytest.raises(X)` equivalent this
directory already vendors.  Cell bodies are unchanged.
"""

import os
import tempfile

from beam_assert import raises
from pathguard import safe_join, PathTraversalError


def test_basic_join():
    with tempfile.TemporaryDirectory() as d:
        out = safe_join(d, "a", "b.txt")
        assert out == os.path.join(os.path.realpath(d), "a", "b.txt")


def test_dotdot_escape_rejected():
    with tempfile.TemporaryDirectory() as d:
        with raises(PathTraversalError):
            safe_join(d, "..", "etc", "passwd")


def test_absolute_part_rejected():
    with tempfile.TemporaryDirectory() as d:
        with raises(PathTraversalError):
            safe_join(d, "/etc/passwd")


def test_symlink_escape_rejected():
    with tempfile.TemporaryDirectory() as d:
        base = os.path.join(d, "base")
        os.makedirs(base)
        target = os.path.join(d, "secret.txt")
        with open(target, "w") as f:
            f.write("secret")
        link = os.path.join(base, "link")
        os.symlink(target, link)
        # reading through link to outside must be rejected when resolved?
        # safe_join resolves; link itself is inside base by name but points outside.
        # Our function resolves symlinks and checks containment -> should reject.
        with raises(PathTraversalError):
            safe_join(base, "link")


def test_valid_nested():
    with tempfile.TemporaryDirectory() as d:
        sub = os.path.join(d, "sub")
        os.makedirs(sub)
        out = safe_join(d, "sub", "file.txt")
        assert out.startswith(os.path.realpath(d) + os.sep)


def test_empty_parts_ignored():
    with tempfile.TemporaryDirectory() as d:
        out = safe_join(d, "", None, "x")
        assert out.endswith("x")


def test_nul_rejected():
    with tempfile.TemporaryDirectory() as d:
        with raises(PathTraversalError):
            safe_join(d, "a\x00b")


def test_base_not_dir():
    with tempfile.TemporaryDirectory() as d:
        f = os.path.join(d, "f")
        open(f, "w").close()
        with raises(PathTraversalError):
            safe_join(f, "x")