DB Integration Test Skill

Discovery

Before writing tests, extract:

• DB engine — Postgres, MySQL, SQLite, MongoDB, etc. (affects transaction syntax, constraint behavior, JSON support)
• Access layer — raw SQL, query builder (Knex, Drizzle), ORM (Prisma, TypeORM, Sequelize)
• Schema — tables, columns, constraints (NOT NULL, UNIQUE, FK, CHECK), indexes
• Test DB strategy — is there an existing test DB, Docker Compose setup, or in-process option (SQLite, pg-mem)?
• Seeding approach — fixtures, factories, or raw inserts? Already established or needs creating?

Test DB Setup — Non-Obvious Decisions

1. Isolate tests with transactions, not table truncation

Transaction rollback is faster and cleaner than truncating between tests: