test(tools): comprehensive test suite for web_search module (+31 tests)

[manus-use]

Summary

Comprehensive test suite for the web_search module (src/manus_agent/tools/web_search.py), which provides the web search capability used by the agent for information gathering.

Test Coverage (31 tests)

SearchEngine base class — 1 test

• Abstract search() raises NotImplementedError

DuckDuckGoSearch — 7 tests

• Async search correctly delegates to synchronous _search_sync
• Result formatting from DuckDuckGo raw response (href + link key variants)
• Empty results handled gracefully
• max_results parameter correctly passed to DDGS
• Missing fields in raw results default to empty strings
• ImportError raised when duckduckgo-search package not installed

GoogleSearch — 6 tests

• Credential initialization (api_key, cx)
• ValueError raised when API key or CX missing
• Empty string credentials also raise
• Valid credentials return empty list (placeholder implementation)

get_search_engine factory — 5 tests

• Config-driven selection: "duckduckgo" → DuckDuckGoSearch
• Config-driven selection: "google" → GoogleSearch
• Unknown engine name falls back to DuckDuckGoSearch
• Direct config argument accepted (bypasses Config.from_file())
• Singleton caching: repeated calls return same instance

web_search_async — 4 tests

• Successful search returns properly formatted results
• Custom max_results override works
• Uses config's tools.max_search_results as default
• Exceptions caught and returned as error result structure

web_search (sync tool) — 5 tests

• Uses _search_sync method when available (avoids event loop)
• Custom max_results passed through
• Exceptions caught and returned as error result
• Falls back to async path when engine lacks _search_sync
• Empty results returned as empty list

Backward compatibility + structure — 3 tests

• web_search_sync is an alias for web_search
• All results contain required keys (title, url, snippet)
• All result values are strings

Technical Notes

• All tests are 100% mocked — no real HTTP calls or search API usage
• Singleton state properly reset between tests via setup_method
• Async tests use explicit event loops (no deprecation warnings)
• Tests document both the DuckDuckGo and Google code paths

Files Changed

• tests/test_web_search.py — new test file (31 tests)