postgres

Overview ¶

Package postgres implements the Den backend for PostgreSQL via jackc/pgx/v5.

Test layering ¶

Three test surfaces cover this backend, each with a distinct purpose:

• **pgxmock unit tests** (this package) for postgres-only error paths: SQLSTATE → den-sentinel mapping, SQL emission for advisory locks and FOR UPDATE variants, mid-stream iterator errors, pool acquire failures. No live PostgreSQL required.
• **engine/parity_test.go** for cross-backend behavior parity (CRUD, query operators, soft-delete, links, transactions). Runs against both SQLite and a real PostgreSQL connection.
• **Real-PostgreSQL integration tests** for concurrency-driven failures the mock cannot model: cursor pinning ("conn busy" on in-loop writes), transaction isolation behavior, advisory-lock release semantics, deadlock retries.

When adding a test, pick the surface that matches the contract under test. pgxmock is the wrong tool for anything concurrency-driven — such tests belong with the live-PG suite.