Testing conventions and in-memory databases

When to use: Writing or debugging tests, choosing unit vs integration style, Postgres/ClickHouse tests, regenerating ClickHouse test schema, or exporting test helpers from packages without pulling test code into production bundles.

Package exports (test code isolation)

Test utilities (fakes, in-memory DB helpers, fixtures) must not be exported from a package’s main entry (src/index.ts).

• Never re-export from ./test/ or ./testing/ in the main src/index.ts
• To expose test helpers, add a /testing subpath in package.json exports:

{
  "exports": {
    ".": "./src/index.ts",
    "./testing": "./src/testing/my-test-helpers.ts"
  }
}