import asyncio import errno import io import json from threading import Event import unittest from unittest import mock from fastapi import FastAPI, HTTPException from fastapi.responses import Response import httpx from PIL import Image from api.errors import install_exception_handlers import api.system as system_module import services.image_service as images class ImageReadErrorTests(unittest.IsolatedAsyncioTestCase): def setUp(self): self.store = mock.Mock() self.store.get_bytes.return_value = b"complete-image" self.store.get_cached_bytes.return_value = None self.store.get_cached_thumbnail.return_value = None for module in (images, system_module): patcher = mock.patch.object(module, "image_storage_service", self.store) patcher.start() self.addCleanup(patcher.stop) self.app = FastAPI() install_exception_handlers(self.app) self.app.include_router(system_module.create_router("regression-test")) @self.app.get("/test/ping") async def ping(): return {"ok": True} async def get(self, url): async with httpx.AsyncClient(transport=httpx.ASGITransport(app=self.app), base_url="http://test") as client: return await client.get(url) async def test_original_is_fully_read_before_response_is_created(self): response = images.get_image_response("2026/10/29/image.webp") self.assertIsInstance(response, Response) self.assertEqual(response.body, b"complete-image") self.assertEqual(response.media_type, "image/webp") self.assertIn("immutable", response.headers["cache-control"]) self.store.get_bytes.assert_called_once_with("2026/10/29/image.webp") async def test_eio_returns_retryable_uncached_503_instead_of_truncated_200(self): self.store.get_bytes.side_effect = OSError(errno.EIO, "private-path-must-not-leak") response = await self.get("/images/2026/10/29/a.png") self.assertEqual(response.status_code, 503) self.assertEqual(response.headers["cache-control"], "no-store") self.assertEqual(response.headers["retry-after"], "10") self.assertNotIn("private-path", response.text) async def test_missing_image_remains_404(self): self.store.get_bytes.side_effect = FileNotFoundError() self.assertEqual((await self.get("/images/a.png")).status_code, 404) async def test_unknown_bug_still_propagates(self): self.store.get_bytes.side_effect = RuntimeError("unexpected bug") with self.assertRaisesRegex(RuntimeError, "unexpected bug"): await self.get("/images/a.png") async def test_thumbnail_bytes_are_read_before_success(self): buffer = io.BytesIO() Image.new("RGB", (640, 480), "blue").save(buffer, format="PNG") self.store.get_bytes.return_value = buffer.getvalue() with mock.patch.object(images, "ensure_thumbnail", side_effect=AssertionError("mount IO")): response = await self.get("/image-thumbnails/a.png") self.assertEqual(response.status_code, 200) with Image.open(io.BytesIO(response.content)) as result: self.assertEqual(result.size, (320, 240)) self.store.cache_thumbnail.assert_called_once_with("a.png", response.content) async def test_thumbnail_read_eio_is_503(self): self.store.get_bytes.side_effect = OSError(errno.EIO, "io") response = await self.get("/image-thumbnails/a.png") self.assertEqual(response.status_code, 503) self.assertEqual(response.headers["cache-control"], "no-store") async def test_invalid_thumbnail_is_422_not_success(self): response = await self.get("/image-thumbnails/a.png") self.assertEqual(response.status_code, 422) async def test_cached_original_and_download_do_not_enter_io_queue(self): self.store.get_cached_bytes.return_value = b"hot-image" with (mock.patch.object(system_module, "_run_image_io", side_effect=AssertionError("IO queue")), mock.patch.object(system_module, "require_admin")): original = await self.get("/images/a.png") download = await self.get("/api/images/download/a.png") self.assertEqual(original.content, b"hot-image") self.assertEqual(download.content, b"hot-image") self.assertEqual(original.status_code, 200) self.assertIn("attachment", download.headers["content-disposition"]) self.store.get_bytes.assert_not_called() async def test_cached_thumbnail_does_not_enter_io_queue(self): self.store.get_cached_thumbnail.return_value = b"hot-thumbnail" with mock.patch.object(system_module, "_run_image_io", side_effect=AssertionError("IO queue")): response = await self.get("/image-thumbnails/a.png") self.assertEqual(response.content, b"hot-thumbnail") self.store.get_bytes.assert_not_called() async def test_hot_original_thumbnail_uses_separate_transform_pool(self): buffer = io.BytesIO() Image.new("RGBA", (512, 512), "green").save(buffer, format="PNG") self.store.get_cached_bytes.return_value = buffer.getvalue() self.store.get_bytes.side_effect = AssertionError("mount read") with mock.patch.object(system_module, "_IMAGE_IO_POOL") as slow_pool: slow_pool.submit.side_effect = AssertionError("blocked IO pool") response = await self.get("/image-thumbnails/a.png") self.assertEqual(response.status_code, 200) with Image.open(io.BytesIO(response.content)) as result: self.assertEqual(result.size, (320, 320)) async def test_image_io_helper_forwards_keyword_arguments(self): result = await system_module._run_image_io(lambda *, limit: limit, limit=3) self.assertEqual(result, 3) async def test_download_keeps_bytes_and_attachment_header(self): with mock.patch.object(system_module, "require_admin"): response = await self.get("/api/images/download/a.webp") self.assertEqual(response.status_code, 200) self.assertEqual(response.content, b"complete-image") self.assertIn("attachment", response.headers["content-disposition"]) self.assertIn("a.webp", response.headers["content-disposition"]) async def test_download_eio_is_not_success(self): self.store.get_bytes.side_effect = OSError(errno.EIO, "io") with mock.patch.object(system_module, "require_admin"): self.assertEqual((await self.get("/api/images/download/a.png")).status_code, 503) async def test_slow_actual_read_is_isolated_and_has_route_timeout(self): release, entered = Event(), Event() def slow_read(_rel): entered.set() release.wait(2) return b"image" self.store.get_bytes.side_effect = slow_read try: with mock.patch.object(system_module, "_IMAGE_IO_TIMEOUT_SECONDS", 0.05): pending = asyncio.create_task(self.get("/images/a.png")) for _ in range(200): if entered.is_set(): break await asyncio.sleep(0.001) self.assertTrue(entered.is_set()) self.assertEqual((await self.get("/test/ping")).status_code, 200) response = await pending self.assertEqual(response.status_code, 503) finally: release.set() async def test_timeout_diagnostic_is_bounded_rate_limited_and_value_free(self): release = Event() def slow_read(private_value): release.wait(2) return private_value try: with (mock.patch.object(system_module, "_IMAGE_IO_TIMEOUT_SECONDS", 0.03), mock.patch.object(system_module, "_last_image_timeout_log_at", float("-inf")), mock.patch.object(system_module.logger, "warning") as warning): for _ in range(2): with self.assertRaises(HTTPException) as caught: await system_module._run_image_io(slow_read, "private-path-and-secret") self.assertEqual(caught.exception.status_code, 503) warning.assert_called_once() entry = warning.call_args.args[0] self.assertEqual(entry["event"], "image_io_timeout") self.assertEqual(entry["worker_state"], "running") self.assertLessEqual(len(entry["stack"]), 10) self.assertIn("slow_read", [f["function"] for f in entry["stack"]]) self.assertNotIn("private-path-and-secret", json.dumps(entry)) self.assertTrue(all(set(f) == {"module", "function", "line"} for f in entry["stack"])) finally: release.set()