test(snowflake): fix the mock patch target so the suite actually runs

[goldmedal]

Summary

tests/connectors/test_snowflake.py has been silently broken: 11 of its 16 tests fail before their bodies run. This fixes the mock patch target, and one assertion the breakage was hiding.

What failure does this repair?

$ uv sync --locked --extra snowflake
$ uv run --no-sync pytest tests/connectors/test_snowflake.py -v
...
AttributeError: module 'wren.connector.snowflake' has no attribute 'snowflake'
11 failed, 5 passed

src/wren/connector/snowflake.py imports the driver inside the functions that use it (import snowflake.connector, with a # noqa: PLC0415), so wren.connector.snowflake never gains a snowflake attribute. The tests patch "wren.connector.snowflake.snowflake.connector.connect", a path that does not exist, and mock.patch fails at attribute resolution before the test body executes.

The fix patches the real module path, "snowflake.connector.connect". The function-local import resolves through sys.modules at call time, so the connector picks up the patched connect. The production import is deliberately function-local — it keeps an optional driver out of module import time — so it is left alone rather than hoisted to make patching convenient.

A second, hidden failure surfaced once the tests ran. test_query_with_limit_slices_result asserted that the connector fetches a full result and slices it to limit rows in Python. query() has not done that since LIMIT pushdown landed: it wraps the SQL as SELECT * FROM (...) AS _wren_sub LIMIT n and returns the driver's table unmodified. The assertion was stale and only survived because the whole file was inert. It is now test_query_with_limit_pushes_limit_into_sql, asserting the pushdown appears in the SQL handed to cursor.execute. The mocked cursor deliberately returns more rows than the limit — a real Snowflake would honour the pushed-down LIMIT — so the test fails if a client-side slice is ever reintroduced.

How is it tested?

tests/connectors/test_snowflake.py: 11 failed / 5 passed → 16 passed.

Note this file does not currently run in CI at all — the connector matrix covers only postgres and mysql. It needs no external service (it is fully mocked), so fixing it is a prerequisite to running it in the default jobs.

Regression check: pytest tests/unit/ --ignore=tests/unit/test_memory.py --ignore=tests/unit/test_mcp_server.py → 1023 passed, 2 skipped. ruff format --check / ruff check clean on src/ and on the touched file.

Duplicate check

No open PR touches tests/connectors/test_snowflake.py. #2593 and #2556 touch src/wren/connector/snowflake.py, which this PR does not modify.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Corrected Snowflake connection handling in authentication and connector creation tests.
  • Updated query limit behavior to apply limits in SQL and return complete query results without additional client-side slicing.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: aec5dee1-2fc9-4fe4-8aac-168dcd7447d6

📥 Commits

Reviewing files that changed from the base of the PR and between a93184d and 6b98872.

📒 Files selected for processing (1)

• core/wren/tests/connectors/test_snowflake.py

---

Walkthrough

Snowflake connector tests now patch the correct connection function and verify that query limits are pushed into SQL without client-side Arrow table slicing.

Changes

Snowflake connector tests

Layer / File(s)	Summary
Connection mock targets core/wren/tests/connectors/test_snowflake.py	Authentication and connector factory tests patch snowflake.connector.connect while preserving connection assertions.
SQL limit pushdown assertions core/wren/tests/connectors/test_snowflake.py	The limit test checks for LIMIT 2 in executed SQL and expects the complete mocked Arrow table.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• Canner/WrenAI#2268: Updates Snowflake connector test mocks and limit expectations.
• Canner/WrenAI#2456: Implements SQL limit pushdown without client-side slicing.
• Canner/WrenAI#2457: Updates connector limit handling and tests for server-side limits.

Suggested reviewers: abdullahharunozturk

Poem

A bunny checks the Snowflake gate,
With proper mocks aligned in place.
SQL now limits what streams through,
The full table hops back true.
Carrots cheer the cleaner trace! 🐇

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: fixing the Snowflake test mock patch target so the suite runs.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/snowflake-test-mock-target

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