# QA procedure: article_title_rules

Package: `test` (black-box, alongside `article_test.go` / `use_case_baseline_test.go` /
`not_found_errors_test.go` / the hasher-domain-interface tests).

## Fakes needed
1. Extend `mockArticleRepo` (`test/article_test.go`) / its shared `failSwitch`
   (`test/fakes_common.go`) so a configured failure can return a specific error, not
   only the generic `errRepositoryFailure`. Today `failSwitch.trigger` always returns
   the same sentinel; add a way to say "the next call to `Create` returns
   `article.ErrInvalidTitle`" specifically, distinct from "the next call to `Create`
   returns a generic repository error" (e.g. a `failNextWith(method string, err error)`
   on `failSwitch`, keeping `errRepositoryFailure` as the default so existing
   generic-failure tests don't change).
2. Add a `createCalled` flag (or equivalent) to `mockArticleRepo` if not already
   present, so a test can assert `Create` was never reached when request-layer
   validation rejects a title first.

## Use-case-level checks (fake repo, no HTTP)
3. `useCases.NewCreateArticleUseCase(repo)`, `CreateArticle(...)` with an empty fake
   repo:
   - Title `strings.Repeat("😀", 2)` (2 runes, 8 bytes) -> `errors.Is(err,
     article.ErrInvalidTitle)`, nothing stored.
   - Title `strings.Repeat("😀", 3)` (3 runes, 12 bytes) -> no error, created,
     `is_online` false, one article stored.
   - Title `strings.Repeat("😀", 200)` (200 runes, 800 bytes) -> no error, created.
     Proves the check counts runes (`utf8.RuneCountInString`), not `len()` bytes.
   - Title `strings.Repeat("😀", 201)` (201 runes, 804 bytes) -> `errors.Is(err,
     article.ErrInvalidTitle)`, nothing stored.
   - Keep the existing ASCII boundary cases in `TestCreateArticleTitleLengthLimit`
     (0/2/3/200/201) passing unchanged, as a regression check that byte length and
     rune length coincide for ASCII.

## HTTP checks (real CreateArticleUseCase over the fake repo, mirroring api/router.go)
4. Call `validator.InitValidator()`.
5. Build `useCases.NewCreateArticleUseCase(fakeRepo)` plus `GetArticleUseCase`,
   `ListArticlesUseCase`, `DeleteArticleUseCase` (real, over the same fake repo). Build
   `article.NewHandler(create, get, list, delete)`. Mount its routes inside a group
   wrapped by `jwtauth.Verifier(token)` + `jwtauth.Authenticator(token)` on a fresh
   `chi.NewRouter()`, with a test `jwtauth.New("HS256", []byte("test-secret"), nil)`, as
   in `api/router.go`.
6. Mint a valid jwt cookie for user id 1 (`token.Encode(map[string]any{"user_id":
   uint32(1)})`, set as the `jwt` cookie on each `httptest.NewRequest`).
7. `POST /v1/article/` with a 2-ASCII-character title (`"ab"`) and a valid body ->
   status `400`, `fakeRepo.createCalled` is false. Assert the body is neither
   `apperr.ArticleTitleErrorMessage` nor `"Failed to create article"`, to keep the two
   400 sources (request-layer vs. domain-layer) distinguishable in the test.
8. `POST /v1/article/` with a 3-ASCII-character title -> status `201`, response body
   decodes to the created article JSON, `is_online` false.
9. `POST /v1/article/` with a 200-ASCII-character title (`strings.Repeat("a", 200)`) ->
   status `201`, created.
10. `POST /v1/article/` with a 201-ASCII-character title -> status `400`, `Create`
    never called.
11. `POST /v1/article/` with a title of 200 repetitions of "😀" (200 runes, 800 bytes)
    and a valid body -> status `201`, created, response JSON's `title` equals the sent
    title.
12. Configure the fake repo (per step 1) so its next `Create` call returns
    `article.ErrInvalidTitle` directly. `POST /v1/article/` with title "Valid Title"
    and a valid body (both well inside 3-200 runes, so `validator.Validate.Struct`
    passes and `CreateArticleUseCase`'s own check would also pass) -> status `400`,
    body `apperr.ArticleTitleErrorMessage + "\n"`. This scenario is deliberately
    artificial: with the rule aligned, no real HTTP input can make
    `CreateArticleUseCase.CreateArticle`'s own check return `article.ErrInvalidTitle`
    once `validator.Validate.Struct` has already accepted the same title, so the only
    way to exercise `Handler.PostArticle`'s mapping branch today is to have the fake
    repository hand back that sentinel directly, standing in for a future or
    repository-level source of the same error.
13. Configure the fake repo to fail on its next `Create` with the generic
    `errRepositoryFailure` (existing `failNext("Create")`). `POST /v1/article/` with
    title "Valid Title" and a valid body -> status `500`, body `"Failed to create
    article\n"` -- regression proof a non-title failure still answers 500.
14. `POST /v1/article/` with no jwt cookie -> status `401` (regression: the route is
    still gated).

## Manual verification (not exercised by the Go test)
- None. This slice has no SPA-visible behaviour and no SMTP involvement.