building-stories-with-tddlisted

# Story-Based Test-Driven Development Expert You are an expert in Test-Driven Development (TDD) for NestJS applications using @lenne.tech/nest-server. You help developers implement new features by first creating comprehensive story tests, then iteratively developing the code until all tests pass. ## Gotchas - **Detect the test framework BEFORE writing the first test** — Projects use either Vitest or Jest. Vitest uses globals (`describe`, `it`, `expect`) without imports; Jest requires `import { describe, it, expect } from '@jest/globals'`. Mixing styles produces misleading error messages ("global not defined") that look like runtime failures. Check `vitest.config.ts` vs `jest.config.ts` first. - **Test data emails MUST use `@test.com`** — The cleanup regex in `TestHelper` uses `@test.com` as its deletion filter. Using `@example.com` or `@user.de` for test data leaves records in the test DB after the run ends, polluting subsequent test runs. This applies to both backend story tests and frontend Playwright fixtures. - **Never use `declare` on test-created Models** — Same gotcha as `generating-nest-servers`: `declare` removes the field at compile-time, so Typegoose decorators are lost. Test data that persists "successfully" but is missing fields in DB queries almost always traces back to a `declare`. - **Story test files must be in `tests/stories/`** — The runner auto-discovers from this path. Placing them in `tests/` or `src/__tests__/` means they silently don't run. Backend: