test_env_containment.py

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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# tests/test_env_containment.py
 
"""
Purpose
-------
OI-515 — verify ``OC_DIAGNOSTICS_*`` env-var containment rules.
 
``_safe_env_path`` rejects empty, NUL-bearing, and over-length paths so
an operator-supplied (or attacker-supplied) env var cannot push pathological
values into the config loader or log directory resolver.
 
``_load_debug_config`` additionally refuses to read a config file larger
than ``_MAX_CONFIG_BYTES`` (10 MiB) and falls back to the in-module
defaults, so a pathological config can't blow memory at import time.
 
Diagnostics
-----------
Domain: TEST
Levels:
    L2 — test lifecycle
 
Contracts
---------
- ``_safe_env_path`` must never return a value containing ``\\0``.
- The config loader must not raise when the file exceeds the cap; it
  must fall back to defaults and mark ``config_source`` accordingly.
"""
 
from __future__ import annotations
 
import os
import sys
import tempfile
import warnings
from pathlib import Path
 
_REPO_ROOT = Path(__file__).resolve().parents[1]
if str(_REPO_ROOT) not in sys.path:
    sys.path.insert(0, str(_REPO_ROOT))
 
from oc_diagnostics import unified_debug as _ud  # noqa: E402
 
 
def test_safe_env_path_accepts_normal_value(monkeypatch):
    """OI-515: typical paths round-trip unchanged through _safe_env_path."""
    monkeypatch.setenv("OC_DIAGNOSTICS_CONFIG", "/tmp/debug_config.json")
    assert _ud._safe_env_path("OC_DIAGNOSTICS_CONFIG") == "/tmp/debug_config.json"
 
 
def test_safe_env_path_rejects_nul_byte(monkeypatch):
    """OI-515: NUL bytes are refused and the env var is treated as unset.
 
    ``os.environ`` itself refuses to store ``\\x00`` on most platforms, so
    we patch ``os.environ.get`` directly to simulate the hostile input.
    """
    def _fake_get(name, default=""):
        return "/tmp/evil\x00payload" if name == "OC_DIAGNOSTICS_CONFIG" else default
 
    monkeypatch.setattr(_ud.os.environ, "get", _fake_get)
    with warnings.catch_warnings(record=True) as captured:
        warnings.simplefilter("always")
        assert _ud._safe_env_path("OC_DIAGNOSTICS_CONFIG") == ""
    assert any("NUL" in str(w.message) for w in captured), captured
 
 
def test_safe_env_path_rejects_over_length(monkeypatch):
    """OI-515: values over _MAX_ENV_PATH_LEN chars are refused."""
    monkeypatch.setenv("OC_DIAGNOSTICS_CONFIG", "x" * (_ud._MAX_ENV_PATH_LEN + 1))
    with warnings.catch_warnings(record=True) as captured:
        warnings.simplefilter("always")
        assert _ud._safe_env_path("OC_DIAGNOSTICS_CONFIG") == ""
    assert any("exceeds" in str(w.message) for w in captured), captured
 
 
def test_safe_env_path_empty_returns_empty(monkeypatch):
    """OI-515: missing or whitespace-only env var returns ``''``."""
    monkeypatch.delenv("OC_DIAGNOSTICS_CONFIG", raising=False)
    assert _ud._safe_env_path("OC_DIAGNOSTICS_CONFIG") == ""
    monkeypatch.setenv("OC_DIAGNOSTICS_CONFIG", "   ")
    assert _ud._safe_env_path("OC_DIAGNOSTICS_CONFIG") == ""
 
 
def test_oversized_config_falls_back_to_defaults(monkeypatch):
    """OI-515: a >10 MiB config file is skipped; defaults are returned."""
    with tempfile.TemporaryDirectory() as tmp:
        oversized = Path(tmp) / "debug_config.json"
        # Write 10 MiB + 1 byte of junk.
        oversized.write_bytes(b"0" * (_ud._MAX_CONFIG_BYTES + 1))
        monkeypatch.setenv("OC_DIAGNOSTICS_CONFIG", str(oversized))
        with warnings.catch_warnings(record=True) as captured:
            warnings.simplefilter("always")
            levels, _colors, _settings, source = _ud._load_debug_config()
        assert "DEFAULTS" in source, source
        assert any("OI-515" in str(w.message) for w in captured), captured
        # Default fallback exposes the minimal "GENERAL" domain only.
        assert "GENERAL" in levels
 
 
def test_normal_sized_config_still_loads(monkeypatch, tmp_path):
    """OI-515: a reasonably-sized config still loads normally."""
    cfg = tmp_path / "debug_config.json"
    cfg.write_text('{"DEBUG_LEVELS": {"TEST": 2}}', encoding="utf-8")
    monkeypatch.setenv("OC_DIAGNOSTICS_CONFIG", str(cfg))
    levels, _colors, _settings, source = _ud._load_debug_config()
    assert str(cfg) in source
    assert levels.get("TEST") == 2