test: cover database migration helpers

[Vinayak1337]

Draft PR for review.

Related bounty: Scottcjn/rustchain-bounties#1589

Summary

• Adds pytest coverage for the database migration runner helpers in tools/db-migrate/migrate.py.
• Covers UP/DOWN parsing, missing DOWN blocks, migration discovery sorting/invalid-file skipping, and SQL block execution with empty statements.

Verification

• /tmp/rustchain-bounty-venv/bin/python -m pytest tests/test_db_migrate.py -q
• /tmp/rustchain-bounty-venv/bin/python -m pytest tests/test_db_migrate.py tests/test_verify_backup.py -q

[github-actions]

Welcome to RustChain! Thanks for your first pull request.

Before we review, please make sure:

• Your PR has a BCOS-L1 or BCOS-L2 label
• New code files include an SPDX license header
• You've tested your changes against the live node

Bounty tiers: Micro (1-10 RTC) | Standard (20-50) | Major (75-100) | Critical (100-150)

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[saim256]

Reviewed current head 54140ef. The new migration-runner tests are scoped to the added test file, import the hyphenated tool module without changing production code, cover UP/DOWN parsing, missing DOWN blocks, migration discovery ordering/name filtering, checksum presence, and SQL-block execution across empty statements. The tests also preserve the existing backup verification coverage requested in the PR body.\n\nValidation run locally on Windows:\n- python -m pytest tests\test_db_migrate.py tests\test_verify_backup.py -q -> 6 passed\n- python -m py_compile tests\test_db_migrate.py tools\db-migrate\migrate.py tests\test_verify_backup.py -> passed\n- git diff --check origin/main...pr-4875 -> passed\n- python tools\bcos_spdx_check.py --base-ref origin/main -> OK

[508704820]

Code Review: Cover Database Migration Helpers

Summary

Adds 97-line test file for db-migrate tool. Tests migration file parsing (UP/DOWN blocks), migration ordering, and SQL execution.

What Works Well

1. importlib.util: Loads migrate module directly
2. UP/DOWN block parsing: Tests the core migration format
3. 97 lines: Good coverage of migration helper logic
4. tmp_path: Clean test isolation

Verdict: Approve

Good test coverage for database migration tooling.

[loganoe]

Reviewed the db-migrate test coverage. The tests exercise migration parsing, discovery ordering/name normalization, and SQL block execution without changing production migration code. I could not run pytest directly in this checkout because tests/conftest.py imports Flask and this environment lacks Flask, but I manually loaded tests/test_db_migrate.py and executed all four test functions successfully: manual db-migrate tests passed.