fix: stop a retrodeck scrape on a failed fetch

tests/test_retrodeck_scraper_errors.py

@@ -0,0 +1,71 @@
+"""A component manifest that could not be read is not a missing one.
+
+The RetroDECK scraper printed "skip" on any HTTP or network error and wrote
+retrodeck.yml without that component: a 503 on pcsx2's manifest removed the
+PS2 BIOS and the pcsx2 standalone core, exit code 0.
+"""
+
+from __future__ import annotations
+
+import io
+import json
+import sys
+import unittest
+import urllib.error
+from pathlib import Path
+from unittest import mock
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+sys.path.insert(0, str(REPO_ROOT))
+
+from scripts.scraper.retrodeck_scraper import Scraper  # noqa: E402
+
+TREE = {"tree": [{"path": "pcsx2", "type": "tree"}, {"path": "ppsspp", "type": "tree"}]}
+
+
+class _Response(io.BytesIO):
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *exc):
+        return False
+
+
+def _opener(failure):
+    def urlopen(req, timeout=0):
+        url = req.full_url
+        if "api.github.com" in url:
+            return _Response(json.dumps(TREE).encode())
+        if "pcsx2" in url and failure is not None:
+            raise failure
+        return _Response(json.dumps({"ppsspp": {"bios": []}}).encode())
+    return urlopen
+
+
+class ManifestErrors(unittest.TestCase):
+    def fetch(self, failure):
+        with mock.patch("urllib.request.urlopen", _opener(failure)):
+            return Scraper()._fetch_remote_manifests()
+
+    def test_a_server_error_stops_the_scrape(self):
+        error = urllib.error.HTTPError("u", 503, "unavailable", {}, None)
+        with self.assertRaises(ConnectionError):
+            self.fetch(error)
+
+    def test_a_dropped_connection_stops_the_scrape(self):
+        with self.assertRaises(ConnectionError):
+            self.fetch(urllib.error.URLError("reset"))
+
+    def test_a_404_is_a_component_without_a_manifest(self):
+        error = urllib.error.HTTPError("u", 404, "not found", {}, None)
+        self.assertEqual([name for name, _ in self.fetch(error)], ["ppsspp"])
+
+    def test_a_truncated_tree_stops_the_scrape(self):
+        TREE["truncated"] = True
+        self.addCleanup(TREE.pop, "truncated")
+        with self.assertRaises(ConnectionError):
+            self.fetch(None)
+
+
+if __name__ == "__main__":
+    unittest.main()