Files
last30days-skill/tests/test_http_v3.py
T
Gabriel Arrillaga 5a2fe5279b fix(http): expand retry budget + use exponential backoff on DNS failure
Transient DNS resolution failures (socket.gaierror, surfaced as
urllib.error.URLError with reason=gaierror) were retried with the
generic URLError handler — linear backoff (2s, 4s, 6s) and bounded by
the caller-passed `retries` parameter. For callers that pass small
retry values (e.g. lib/reddit.py::_subreddit_search uses retries=2), a
single first-attempt DNS hiccup followed by one quick retry on the
still-flaky resolver would exhaust the retry budget and wipe a whole
subreddit sweep — which the caller's broad `except Exception` then
silent-empties as `[]`.

Fix:
- Distinguish URLError-with-gaierror-reason from generic URLError via
  a new `_is_dns_failure()` helper.
- For DNS failures, use exponential backoff (1s, 2s, 4s, ...) instead
  of the linear default.
- For DNS failures, expand the effective retry budget to at least
  MIN_DNS_RETRIES (=3) on first occurrence, so callers that passed
  `retries=2` still get a meaningful retry budget for the transient
  case. Non-DNS URLErrors and HTTPErrors keep the caller's value.
- DNS attempts are counted separately (`dns_attempts`) so unrelated
  URLError or OSError failures within the same call don't accidentally
  expand the budget further.

Reported during a community-signal pass where the Reddit subreddit
sweep silently returned zero items after a first-round transient DNS
hiccup. The fix lives at the http layer (where the retry loop is)
rather than per-source so every caller benefits.

Tests:
- Verifies a caller-passed retries=2 still gets MIN_DNS_RETRIES=3
  attempts on gaierror.
- Verifies gaierror-then-success returns successfully on attempt 2.
- Verifies the exponential-backoff sleep pattern (1s, 2s) on the
  retry attempts before exhaustion.
- Verifies a non-DNS URLError (ConnectionRefusedError reason) does
  NOT expand the retry budget — only true DNS failures do.

All 12 http tests pass (8 baseline + 4 new). No regressions in the
broader test suite (1373 pass / 14 fail, vs 1369 pass / 14 fail on
main — the 14 failures are pre-existing and unrelated to this PR).
2026-05-16 20:54:14 -07:00

183 lines
7.7 KiB
Python

import sys
import urllib.error
import unittest
from pathlib import Path
from unittest.mock import patch, MagicMock
sys.path.insert(0, str(Path(__file__).resolve().parents[1] / "skills" / "last30days" / "scripts"))
from lib import http
class Test429RetryLimit(unittest.TestCase):
"""429 retries must be capped at max_429_retries to avoid wasting latency."""
@patch("lib.http.urllib.request.urlopen")
@patch("lib.http.time.sleep") # Don't actually sleep in tests
def test_429_retries_limited_to_2_by_default(self, mock_sleep, mock_urlopen):
"""With default max_429_retries=2, should attempt 2 times then raise."""
error = urllib.error.HTTPError(
"http://example.com", 429, "Too Many Requests", {}, None
)
mock_urlopen.side_effect = error
with self.assertRaises(http.HTTPError) as ctx:
http.request("GET", "http://example.com", retries=5)
self.assertEqual(ctx.exception.status_code, 429)
# Should be called exactly 2 times (initial + 1 retry), not 5
self.assertEqual(mock_urlopen.call_count, 2)
@patch("lib.http.urllib.request.urlopen")
@patch("lib.http.time.sleep")
def test_non_429_errors_still_use_full_retries(self, mock_sleep, mock_urlopen):
"""500 errors should still retry up to the full retries count."""
error = urllib.error.HTTPError(
"http://example.com", 500, "Internal Server Error", {}, None
)
mock_urlopen.side_effect = error
with self.assertRaises(http.HTTPError):
http.request("GET", "http://example.com", retries=3)
self.assertEqual(mock_urlopen.call_count, 3)
def _mock_response(body: str = '{"ok": true}', status: int = 200):
resp = MagicMock()
resp.__enter__ = MagicMock(return_value=resp)
resp.__exit__ = MagicMock(return_value=False)
resp.read.return_value = body.encode("utf-8")
resp.status = status
return resp
class TestParamsEncoding(unittest.TestCase):
"""request() should urlencode the params dict into the URL."""
def _sent_url(self, mock_urlopen) -> str:
request_arg = mock_urlopen.call_args[0][0]
return request_arg.full_url
@patch("lib.http.urllib.request.urlopen")
def test_params_appended_to_url(self, mock_urlopen):
mock_urlopen.return_value = _mock_response()
http.get("https://api.example.com/search", params={"q": "test", "limit": 10})
sent_url = self._sent_url(mock_urlopen)
self.assertIn("q=test", sent_url)
self.assertIn("limit=10", sent_url)
@patch("lib.http.urllib.request.urlopen")
def test_params_appended_with_existing_query_string(self, mock_urlopen):
mock_urlopen.return_value = _mock_response()
http.get("https://api.example.com/search?api_key=secret", params={"q": "test"})
sent_url = self._sent_url(mock_urlopen)
self.assertTrue(sent_url.startswith("https://api.example.com/search?api_key=secret&"))
self.assertIn("q=test", sent_url)
@patch("lib.http.urllib.request.urlopen")
def test_none_values_dropped(self, mock_urlopen):
mock_urlopen.return_value = _mock_response()
http.get("https://api.example.com/search", params={"q": "test", "filter": None})
sent_url = self._sent_url(mock_urlopen)
self.assertIn("q=test", sent_url)
self.assertNotIn("filter", sent_url)
@patch("lib.http.urllib.request.urlopen")
def test_empty_params_leaves_url_unchanged(self, mock_urlopen):
mock_urlopen.return_value = _mock_response()
http.get("https://api.example.com/search", params={})
sent_url = self._sent_url(mock_urlopen)
self.assertEqual(sent_url, "https://api.example.com/search")
@patch("lib.http.urllib.request.urlopen")
def test_no_params_kwarg_leaves_url_unchanged(self, mock_urlopen):
mock_urlopen.return_value = _mock_response()
http.get("https://api.example.com/search")
sent_url = self._sent_url(mock_urlopen)
self.assertEqual(sent_url, "https://api.example.com/search")
@patch("lib.http.urllib.request.urlopen")
def test_int_and_bool_params_stringified(self, mock_urlopen):
mock_urlopen.return_value = _mock_response()
http.get("https://api.example.com/search", params={"count": 25, "raw": True})
sent_url = self._sent_url(mock_urlopen)
self.assertIn("count=25", sent_url)
self.assertIn("raw=True", sent_url)
class TestDNSResolutionRetry(unittest.TestCase):
"""DNS resolution failures (gaierror) must retry with exponential backoff.
Caller-passed `retries` values smaller than MIN_DNS_RETRIES are expanded
on the first gaierror so a transient resolution failure doesn't wipe a
request just because the caller passed retries=2.
"""
@patch("lib.http.urllib.request.urlopen")
@patch("lib.http.time.sleep")
def test_gaierror_retries_up_to_min_dns_retries_even_when_caller_passes_fewer(
self, mock_sleep, mock_urlopen
):
"""Caller passed retries=2; gaierror should still get MIN_DNS_RETRIES attempts."""
import socket
err = urllib.error.URLError(socket.gaierror(-2, "Name or service not known"))
mock_urlopen.side_effect = err
with self.assertRaises(http.HTTPError):
http.request("GET", "http://nonexistent.example", retries=2)
# Caller passed retries=2, but the budget expanded to MIN_DNS_RETRIES=3.
self.assertEqual(mock_urlopen.call_count, http.MIN_DNS_RETRIES)
@patch("lib.http.urllib.request.urlopen")
@patch("lib.http.time.sleep")
def test_gaierror_succeeds_after_transient_failure(self, mock_sleep, mock_urlopen):
"""gaierror on attempt 1, then success — should NOT raise."""
import socket
success_response = MagicMock()
success_response.read.return_value = b'{"ok": true}'
success_response.status = 200
success_response.__enter__ = lambda self: self
success_response.__exit__ = lambda *args: None
err = urllib.error.URLError(socket.gaierror(-2, "Name or service not known"))
mock_urlopen.side_effect = [err, success_response]
result = http.request("GET", "http://flaky.example", retries=2)
self.assertEqual(result, {"ok": True})
self.assertEqual(mock_urlopen.call_count, 2)
@patch("lib.http.urllib.request.urlopen")
@patch("lib.http.time.sleep")
def test_gaierror_uses_exponential_backoff(self, mock_sleep, mock_urlopen):
"""Backoff delays for gaierror should be 1s, 2s, 4s — not the linear default."""
import socket
err = urllib.error.URLError(socket.gaierror(-2, "Name or service not known"))
mock_urlopen.side_effect = err
with self.assertRaises(http.HTTPError):
http.request("GET", "http://nonexistent.example", retries=3)
# Expected sleep calls: 1s (after attempt 1), 2s (after attempt 2).
# No sleep after the final attempt (the loop exits to raise).
sleep_delays = [call.args[0] for call in mock_sleep.call_args_list]
self.assertEqual(sleep_delays, [1, 2])
@patch("lib.http.urllib.request.urlopen")
@patch("lib.http.time.sleep")
def test_non_dns_urlerror_uses_linear_backoff_not_dns_branch(
self, mock_sleep, mock_urlopen
):
"""A URLError that's NOT a gaierror must NOT expand the retry budget."""
# ConnectionRefusedError-style URLError reason (not gaierror)
err = urllib.error.URLError(ConnectionRefusedError(111, "Connection refused"))
mock_urlopen.side_effect = err
with self.assertRaises(http.HTTPError):
http.request("GET", "http://refused.example", retries=2)
# Caller passed retries=2, and non-DNS URLError doesn't expand it.
self.assertEqual(mock_urlopen.call_count, 2)