fix(oracle): strip trailing semicolon before subquery-wrapping

[Bartok9]

Summary

• Both OracleConnector.query (when a limit is given) and OracleConnector.dry_run wrap user SQL as SELECT * FROM ({sql}) t WHERE ROWNUM <= N. When the user SQL ends in ;, the subquery is invalid and Oracle raises ORA-00911: invalid character.
• User-facing impact: running (with a row limit) or validating a query that ends in a semicolon fails on Oracle even though the same query executes fine standalone.

Motivation

The sibling connectors already strip a trailing semicolon before subquery-wrapping: postgres, canner, trino, clickhouse all have a _strip_trailing_semicolon helper. Oracle wrapped raw SQL in both code paths.

The fix adds _strip_trailing_semicolon() (same [;\s]+\Z regex as the postgres connector) and applies it in both query() and dry_run(). Only the terminating run of semicolons/whitespace is stripped, so semicolons inside string literals (SELECT 'a;b') are preserved.

Verification

• uv run --no-sync pytest tests/unit/test_oracle_semicolon.py -q — 4 passed (with the oracle extra installed).

Real behavior proof

Regression test core/wren/tests/unit/test_oracle_semicolon.py asserts the executed SQL and FAILS without the fix. It pytest.importorskip("oracledb") so it skips cleanly when the oracle extra isn't installed.

Without the fix (helper absent):

ImportError: cannot import name '_strip_trailing_semicolon' from 'wren.connector.oracle'
1 error

With the fix:

....                                                                     [100%]
4 passed in 0.21s

The query test asserts the executed SQL is exactly SELECT * FROM (SELECT 1) t WHERE ROWNUM <= 5 (no ;)); the dry_run test asserts ... WHERE ROWNUM <= 0.

Scope / risk

• Touches only core/wren/src/wren/connector/oracle.py (Apache-2.0 path) + a new unit test.
• Does NOT touch type parsing or connection logic.
• The no-limit query() path (which doesn't wrap) is unchanged; string-literal semicolons preserved (covered by a helper test).

Summary by CodeRabbit

• Bug Fixes
  • Improved Oracle query handling so statements ending with a trailing semicolon no longer fail when used in limited queries or dry runs.
  • Preserved semicolons inside string literals while only trimming unnecessary trailing semicolons and surrounding whitespace.
• Tests
  • Added coverage for Oracle SQL wrapping behavior, including trailing-semicolon handling and unchanged behavior when no trailing semicolon is present.

[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

Run ID: b2ec4c2e-3f66-4f9b-bf51-b7dce38b6318

📥 Commits

Reviewing files that changed from the base of the PR and between 3122f4f and c5d8595.

📒 Files selected for processing (2)

• core/wren/src/wren/connector/oracle.py
• core/wren/tests/unit/test_oracle_semicolon.py

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Walkthrough

Adds a _strip_trailing_semicolon(sql) helper to the Oracle connector that uses a compiled regex to remove trailing semicolons and whitespace. The helper is applied in OracleConnector.query (ROWNUM <= N wrapping) and dry_run (ROWNUM <= 0 wrapping). A new unit test module validates all cases via mocked cursor.

Changes

Oracle Trailing Semicolon Stripping

Layer / File(s)	Summary
Helper and connector usage core/wren/src/wren/connector/oracle.py	Adds import re, defines _strip_trailing_semicolon(sql) with a compiled trailing-semicolon regex, and applies it in OracleConnector.query and dry_run when building Oracle subquery wrappers.
Unit tests core/wren/tests/unit/test_oracle_semicolon.py	New test module that constructs a mock OracleConnector, captures SQL passed to cursor.execute, and asserts correct ROWNUM wrapping after semicolon removal for query, dry_run, and the helper function directly.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• Canner/WrenAI#2407: Applies the same trailing-semicolon stripping pattern to another connector's query and dry_run SQL wrapping logic.

Suggested reviewers

• goldmedal

🐇 A semicolon lurked at the end of the line,
Confusing poor Oracle time after time.
But now a regex swoops in with flair,
Strips the stray punctuation right out of there.
No more ORA errors, the query runs fine! 🎉

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 22.22% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main fix: stripping trailing semicolons before Oracle subquery wrapping.
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 unit tests (beta)

• Create PR with unit tests

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