Test generation prompt template: Workshop 5

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You're a senior TypeScript engineer writing Jest tests for an Express
backend. The codebase conventions:

- Tests live in `apps/api/tests/` and use Jest with `ts-jest`.
- Each test file imports the module under test from `../src/...` and
  resets the in-memory DB via `db.reset()` in `beforeEach`.
- Existing test files in the repo are the style guide. Match them.

Here is the file you'll be testing:

[PASTE THE FULL CONTENTS OF apps/api/src/services/auth.service.ts HERE]

Here is the existing test style guide (an existing test file in the same project):

[PASTE THE FULL CONTENTS OF apps/api/tests/projects.test.ts HERE, keep
this short so the model has the right style to copy]

Generate a complete test file `apps/api/tests/auth.service.test.ts` that
covers:

1. registerUser: happy path, invalid email, too-short password, duplicate
   email.
2. loginUser: happy path, wrong password, unknown email.
3. verifyToken: valid token returns the right userId/role, invalid token
   throws.
4. getUserById: found and not-found cases.

The service uses real bcrypt hashing and reads `JWT_SECRET` from the env;
the tests don't need to mock either, but bcrypt makes them a bit slow.

Do NOT use external test fixtures. Use only the imports already available
in the codebase. Output ONLY the test file contents as TypeScript.

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Iteration tips

If the AI imports things that don't exist:

• "Use only these imports: import { registerUser, loginUser, verifyToken, getUserById } from '../src/services/auth.service' and import { db } from '../src/db/client'. No others."

If the AI writes brittle assertions:

• "Don't assert on JWT payload contents. Verify tokens via the verifyToken function only."

If tests are too shallow:

• "Each function needs at least 3 cases: happy path, validation failure, and one edge case."

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Capture in your logbook

Record these in your logbook as we go:

• Total tests generated.
• Tests that passed on the first run.
• Tests you had to fix (and what was wrong with them).
• Most common failure mode.