"""DDG lite fallback: free search must survive an html.duckduckgo.com throttle. The field failure (Alex, 1.5.4): DDG's html endpoint 202-throttled and a subscription-only user (no Gemini/OpenAI key) got "No results / no search backend configured" for every query, free search had a single point of failure. The seal: on html-202 OR html-parse-drift (200 with zero entries), search_ddg falls to lite.duckduckgo.com; only BOTH throttling raises DDGRateLimited. Network is mocked; the lite fixture is the real markup shape captured live 2026-07-07 (single-quoted class attrs, direct hrefs, paired snippet rows). """ import asyncio import httpx import pytest from backend.apps.agents.tools.web import WebSearchTool, DDGRateLimited from backend.apps.agents.tools.search_ddg_lite import parse_lite_results P_LITE_BODY = """

1.	Claude Fable \\ Anthropic
	Claude Fable 5 is a real step forward.
2.	TechCrunch story
	Second snippet text.

""" P_HTML_202_BODY = "anomaly detected, challenge page" class p_FakeResp: def __init__(self, status_code: int, text: str): self.status_code = status_code self.text = text def raise_for_status(self): if self.status_code >= 400: raise httpx.HTTPStatusError("err", request=None, response=None) class p_RoutedClient: """Fake AsyncClient that answers per-URL, so the html and lite endpoints can behave differently in one test.""" def __init__(self, routes: dict): self.routes = routes async def __aenter__(self): return self async def __aexit__(self, *a): return False async def post(self, url, *a, **k): for key, resp in self.routes.items(): if key in url: return resp raise AssertionError(f"unexpected URL {url}") def p_route(monkeypatch, routes: dict): monkeypatch.setattr(httpx, "AsyncClient", lambda *a, **k: p_RoutedClient(routes)) def test_lite_parser_on_real_shape(): out = parse_lite_results(P_LITE_BODY, 5) assert "[1] Claude Fable \\ Anthropic" in out assert "https://www.anthropic.com/claude/fable" in out assert "Claude Fable 5 is a real step forward." in out assert "[2] TechCrunch story" in out assert "Second snippet text." in out def test_lite_parser_respects_num_results(): out = parse_lite_results(P_LITE_BODY, 1) assert "[1]" in out and "[2]" not in out def test_html_throttle_falls_to_lite(monkeypatch): p_route(monkeypatch, { "html.duckduckgo.com": p_FakeResp(202, P_HTML_202_BODY), "lite.duckduckgo.com": p_FakeResp(200, P_LITE_BODY), }) out = asyncio.run(WebSearchTool.search_ddg("q", 5)) assert "Claude Fable" in out # lite answered despite html throttle def test_both_throttled_raises_rate_limited(monkeypatch): p_route(monkeypatch, { "html.duckduckgo.com": p_FakeResp(202, P_HTML_202_BODY), "lite.duckduckgo.com": p_FakeResp(202, P_HTML_202_BODY), }) with pytest.raises(DDGRateLimited): asyncio.run(WebSearchTool.search_ddg("q", 5)) def test_html_markup_drift_falls_to_lite(monkeypatch): p_route(monkeypatch, { "html.duckduckgo.com": p_FakeResp(200, "totally new markup"), "lite.duckduckgo.com": p_FakeResp(200, P_LITE_BODY), }) out = asyncio.run(WebSearchTool.search_ddg("q", 5)) assert "Claude Fable" in out # drift didn't silently become "no results"