hermes-agent/tests/plugins/image_gen/test_openai_provider.py
kshitijk4poor c1826e2690 fix(image-gen): route local-input credential guard through one shared chokepoint + cover xai (#57698)
Follow-up to the per-provider guards. Three improvements from review:

1. Extract agent.file_safety.raise_if_read_blocked() as a single shared
   chokepoint and route the OpenAI, OpenRouter, and (newly) xAI image
   providers through it, replacing the 3x-duplicated inline try/except.
   Fixes the whole bug class: xai/_xai_image_field read a model-supplied
   local path via open() with no guard — the same vulnerability the PR
   fixed for OpenAI/OpenRouter, in a sibling provider it missed.
2. Strengthen the regression tests from pass-on-any-ValueError to true
   security invariants: spy open()/read_bytes() and assert the blocked
   credential is NEVER read; add negative controls (legit local image
   still loads; remote/data: URIs pass through unguarded) so a
   block-everything regression can't pass.
3. Guard is best-effort by design (defense-in-depth, not a security
   boundary) — documented on the shared helper.

- agent/file_safety.py: raise_if_read_blocked()
- plugins/image_gen/{openai,openrouter,xai}: route through helper
- tests: no-read spies + negative controls across all three providers
2026-07-03 18:47:53 +05:30

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"""Tests for the bundled OpenAI image_gen plugin (gpt-image-2, three tiers)."""
from __future__ import annotations
from pathlib import Path
from types import SimpleNamespace
from unittest.mock import MagicMock, patch
import pytest
import plugins.image_gen.openai as openai_plugin
# 1×1 transparent PNG — valid bytes for save_b64_image()
_PNG_HEX = (
"89504e470d0a1a0a0000000d49484452000000010000000108060000001f15c4"
"890000000d49444154789c6300010000000500010d0a2db40000000049454e44"
"ae426082"
)
def _b64_png() -> str:
import base64
return base64.b64encode(bytes.fromhex(_PNG_HEX)).decode()
def _fake_response(*, b64=None, url=None, revised_prompt=None):
item = SimpleNamespace(b64_json=b64, url=url, revised_prompt=revised_prompt)
return SimpleNamespace(data=[item])
@pytest.fixture(autouse=True)
def _tmp_hermes_home(tmp_path, monkeypatch):
monkeypatch.setenv("HERMES_HOME", str(tmp_path))
yield tmp_path
@pytest.fixture
def provider(monkeypatch):
monkeypatch.setenv("OPENAI_API_KEY", "test-key")
return openai_plugin.OpenAIImageGenProvider()
def _patched_openai(fake_client: MagicMock):
fake_openai = MagicMock()
fake_openai.OpenAI.return_value = fake_client
return patch.dict("sys.modules", {"openai": fake_openai})
# ── Metadata ────────────────────────────────────────────────────────────────
class TestMetadata:
def test_name(self, provider):
assert provider.name == "openai"
def test_default_model(self, provider):
assert provider.default_model() == "gpt-image-2-medium"
def test_list_models_three_tiers(self, provider):
ids = [m["id"] for m in provider.list_models()]
assert ids == ["gpt-image-2-low", "gpt-image-2-medium", "gpt-image-2-high"]
def test_catalog_entries_have_display_speed_strengths(self, provider):
for entry in provider.list_models():
assert entry["display"].startswith("GPT Image 2")
assert entry["speed"]
assert entry["strengths"]
# ── Availability ────────────────────────────────────────────────────────────
class TestAvailability:
def test_no_api_key_unavailable(self, monkeypatch):
monkeypatch.delenv("OPENAI_API_KEY", raising=False)
assert openai_plugin.OpenAIImageGenProvider().is_available() is False
def test_api_key_set_available(self, monkeypatch):
monkeypatch.setenv("OPENAI_API_KEY", "test")
assert openai_plugin.OpenAIImageGenProvider().is_available() is True
# ── Model resolution ────────────────────────────────────────────────────────
class TestModelResolution:
def test_default_is_medium(self):
model_id, meta = openai_plugin._resolve_model()
assert model_id == "gpt-image-2-medium"
assert meta["quality"] == "medium"
def test_env_var_override(self, monkeypatch):
monkeypatch.setenv("OPENAI_IMAGE_MODEL", "gpt-image-2-high")
model_id, meta = openai_plugin._resolve_model()
assert model_id == "gpt-image-2-high"
assert meta["quality"] == "high"
def test_env_var_unknown_falls_back(self, monkeypatch):
monkeypatch.setenv("OPENAI_IMAGE_MODEL", "bogus-tier")
model_id, _ = openai_plugin._resolve_model()
assert model_id == openai_plugin.DEFAULT_MODEL
def test_config_openai_model(self, tmp_path):
import yaml
(tmp_path / "config.yaml").write_text(
yaml.safe_dump({"image_gen": {"openai": {"model": "gpt-image-2-low"}}})
)
model_id, meta = openai_plugin._resolve_model()
assert model_id == "gpt-image-2-low"
assert meta["quality"] == "low"
def test_config_top_level_model(self, tmp_path):
"""``image_gen.model: gpt-image-2-high`` also works (top-level)."""
import yaml
(tmp_path / "config.yaml").write_text(
yaml.safe_dump({"image_gen": {"model": "gpt-image-2-high"}})
)
model_id, meta = openai_plugin._resolve_model()
assert model_id == "gpt-image-2-high"
assert meta["quality"] == "high"
# ── Generate ────────────────────────────────────────────────────────────────
class TestSourceImageLoading:
def test_load_image_bytes_blocks_credential_store(self, tmp_path, monkeypatch):
hermes_home = tmp_path / ".hermes"
hermes_home.mkdir()
auth_json = hermes_home / "auth.json"
auth_json.write_text('{"api_key":"sk-secret"}', encoding="utf-8")
monkeypatch.setenv("HERMES_HOME", str(hermes_home))
with pytest.raises(ValueError, match="credential store"):
openai_plugin._load_image_bytes(str(auth_json))
def test_load_image_bytes_never_opens_blocked_credential(self, tmp_path, monkeypatch):
"""The guard must fire BEFORE the file is opened — a credential store
must never be read into memory (#57698). Spy builtins.open and assert
it is never called for the blocked path."""
hermes_home = tmp_path / ".hermes"
hermes_home.mkdir()
auth_json = hermes_home / "auth.json"
auth_json.write_text('{"api_key":"sk-secret"}', encoding="utf-8")
monkeypatch.setenv("HERMES_HOME", str(hermes_home))
import builtins
real_open = builtins.open
opened: list = []
def _spy_open(file, *a, **k):
opened.append(str(file))
return real_open(file, *a, **k)
monkeypatch.setattr(builtins, "open", _spy_open)
with pytest.raises(ValueError, match="credential store"):
openai_plugin._load_image_bytes(str(auth_json))
assert str(auth_json) not in opened, "blocked credential must never be opened"
def test_load_image_bytes_allows_legit_local_image(self, tmp_path, monkeypatch):
"""Negative control: a legitimate local image path is NOT blocked and
loads normally — proves the guard doesn't over-fire on everything."""
hermes_home = tmp_path / ".hermes"
hermes_home.mkdir()
monkeypatch.setenv("HERMES_HOME", str(hermes_home))
img = tmp_path / "pic.png"
img.write_bytes(b"\x89PNG\r\n\x1a\nfake-image-bytes")
data, name = openai_plugin._load_image_bytes(str(img))
assert data == b"\x89PNG\r\n\x1a\nfake-image-bytes"
assert name == "pic.png"
def test_load_image_bytes_passthrough_data_uri_not_blocked(self, tmp_path, monkeypatch):
"""Negative control: data: URIs are decoded, never routed through the
local-path guard (the guard only applies to local file reads)."""
import base64
hermes_home = tmp_path / ".hermes"
hermes_home.mkdir()
monkeypatch.setenv("HERMES_HOME", str(hermes_home))
b64 = base64.b64encode(b"xyz").decode("ascii")
data, name = openai_plugin._load_image_bytes(f"data:image/png;base64,{b64}")
assert data == b"xyz"
assert name.endswith(".png")
class TestGenerate:
def test_empty_prompt_rejected(self, provider):
result = provider.generate("", aspect_ratio="square")
assert result["success"] is False
assert result["error_type"] == "invalid_argument"
def test_missing_api_key(self, monkeypatch):
monkeypatch.delenv("OPENAI_API_KEY", raising=False)
result = openai_plugin.OpenAIImageGenProvider().generate("a cat")
assert result["success"] is False
assert result["error_type"] == "auth_required"
def test_b64_saves_to_cache(self, provider, tmp_path):
png_bytes = bytes.fromhex(_PNG_HEX)
fake_client = MagicMock()
fake_client.images.generate.return_value = _fake_response(b64=_b64_png())
with _patched_openai(fake_client):
result = provider.generate("a cat", aspect_ratio="landscape")
assert result["success"] is True
assert result["model"] == "gpt-image-2-medium"
assert result["aspect_ratio"] == "landscape"
assert result["provider"] == "openai"
assert result["quality"] == "medium"
saved = Path(result["image"])
assert saved.exists()
assert saved.parent == tmp_path / "cache" / "images"
assert saved.read_bytes() == png_bytes
call_kwargs = fake_client.images.generate.call_args.kwargs
# All tiers hit the single underlying API model.
assert call_kwargs["model"] == "gpt-image-2"
assert call_kwargs["quality"] == "medium"
assert call_kwargs["size"] == "1536x1024"
# gpt-image-2 rejects response_format — we must NOT send it.
assert "response_format" not in call_kwargs
@pytest.mark.parametrize("tier,expected_quality", [
("gpt-image-2-low", "low"),
("gpt-image-2-medium", "medium"),
("gpt-image-2-high", "high"),
])
def test_tier_maps_to_quality(self, provider, monkeypatch, tier, expected_quality):
monkeypatch.setenv("OPENAI_IMAGE_MODEL", tier)
fake_client = MagicMock()
fake_client.images.generate.return_value = _fake_response(b64=_b64_png())
with _patched_openai(fake_client):
result = provider.generate("a cat")
assert result["model"] == tier
assert result["quality"] == expected_quality
assert fake_client.images.generate.call_args.kwargs["quality"] == expected_quality
# Always the same underlying API model regardless of tier.
assert fake_client.images.generate.call_args.kwargs["model"] == "gpt-image-2"
@pytest.mark.parametrize("aspect,expected_size", [
("landscape", "1536x1024"),
("square", "1024x1024"),
("portrait", "1024x1536"),
])
def test_aspect_ratio_mapping(self, provider, aspect, expected_size):
fake_client = MagicMock()
fake_client.images.generate.return_value = _fake_response(b64=_b64_png())
with _patched_openai(fake_client):
provider.generate("a cat", aspect_ratio=aspect)
assert fake_client.images.generate.call_args.kwargs["size"] == expected_size
def test_revised_prompt_passed_through(self, provider):
fake_client = MagicMock()
fake_client.images.generate.return_value = _fake_response(
b64=_b64_png(), revised_prompt="A photo of a cat",
)
with _patched_openai(fake_client):
result = provider.generate("a cat")
assert result["revised_prompt"] == "A photo of a cat"
def test_api_error_returns_error_response(self, provider):
fake_client = MagicMock()
fake_client.images.generate.side_effect = RuntimeError("boom")
with _patched_openai(fake_client):
result = provider.generate("a cat")
assert result["success"] is False
assert result["error_type"] == "api_error"
assert "boom" in result["error"]
def test_empty_response_data(self, provider):
fake_client = MagicMock()
fake_client.images.generate.return_value = SimpleNamespace(data=[])
with _patched_openai(fake_client):
result = provider.generate("a cat")
assert result["success"] is False
assert result["error_type"] == "empty_response"
def test_url_response_is_cached_locally(self, provider):
"""OpenAI URL response (if API ever returns one) is cached locally.
Pre-fix this asserted the bare URL passed through; symmetric to the
xAI #26942 fix. Even though gpt-image-2 returns b64 today, every
``image_gen`` provider must guarantee the gateway gets a stable
file path so ephemeral signed URLs can't expire mid-flight.
"""
fake_client = MagicMock()
fake_client.images.generate.return_value = _fake_response(
b64=None, url="https://example.com/img.png",
)
with _patched_openai(fake_client), patch(
"plugins.image_gen.openai.save_url_image",
return_value=Path("/tmp/openai_gpt-image-2_20260524_000000_deadbeef.png"),
) as mock_save_url:
result = provider.generate("a cat")
assert result["success"] is True
assert result["image"].startswith("/")
assert "example.com" not in result["image"]
mock_save_url.assert_called_once()
def test_url_response_falls_back_to_bare_url_when_download_fails(self, provider):
"""Cache failure must not turn into a tool error — symmetric with xAI."""
import requests as req_lib
fake_client = MagicMock()
fake_client.images.generate.return_value = _fake_response(
b64=None, url="https://example.com/img.png",
)
with _patched_openai(fake_client), patch(
"plugins.image_gen.openai.save_url_image",
side_effect=req_lib.HTTPError("404 from CDN"),
):
result = provider.generate("a cat")
assert result["success"] is True
assert result["image"] == "https://example.com/img.png"