# Test Model: Post Likes

Feature: Like/unlike toggle on blog posts with per-user tracking, session-based
guest identification, and anti-bot protection via JS-only POST.

## Unit Test Cases

### TogglePostLikeUseCase

#### TC-UNIT-822: TogglePostLikeUseCase — Like first time
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/application/test_toggle_like.py::TestTogglePostLikeUseCase::test_like_post_first_time`
- **Preconditions:** Post exists, no existing like for this user
- **Steps:** Execute toggle with valid post_id and liked_by
- **Expected:**
  - `add_like` called once
  - `remove_like` not called
  - Response DTO has `like_count=1`
- **Last Verified:** 2026-05-10

#### TC-UNIT-823: TogglePostLikeUseCase — Unlike (already liked)
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/application/test_toggle_like.py::TestTogglePostLikeUseCase::test_unlike_post_already_liked`
- **Preconditions:** Post exists, existing like found for this user
- **Steps:** Execute toggle with same post_id and liked_by
- **Expected:**
  - `remove_like` called once
  - `add_like` not called
  - Response DTO has `like_count=0`
- **Last Verified:** 2026-05-10

#### TC-UNIT-824: TogglePostLikeUseCase — Post not found
- **Type:** Negative
- **Layer:** Unit
- **File:** `unit/application/test_toggle_like.py::TestTogglePostLikeUseCase::test_like_post_not_found`
- **Preconditions:** Repository returns None for post lookup
- **Steps:** Execute toggle with non-existent post_id
- **Expected:** `NotFoundException` raised
- **Last Verified:** 2026-05-10

#### TC-UNIT-825: TogglePostLikeUseCase — Guest via device_id
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/application/test_toggle_like.py::TestTogglePostLikeUseCase::test_like_as_guest_with_device_id`
- **Preconditions:** Post exists, no existing like, liked_by set to device_id
- **Steps:** Execute toggle with device_id instead of user_id
- **Expected:**
  - Like created with `liked_by == device_id`
  - Response DTO has `like_count=1`
- **Last Verified:** 2026-05-10

#### TC-UNIT-828: TogglePostLikeUseCase — Identity isolation
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/application/test_toggle_like.py::TestTogglePostLikeUseCase::test_two_users_can_both_like`
- **Preconditions:** Post exists, user1 likes first
- **Steps:** User2 toggles like on same post
- **Expected:**
  - User2's like added (separate identity)
  - `like_count=2`
- **Last Verified:** 2026-05-10

### Domain Entities

#### TC-UNIT-826: PostLike entity — valid creation
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_like_entity.py::TestPostLikeEntity::test_post_like_creation`
- **Preconditions:** Valid post_id and liked_by values
- **Steps:** Create PostLike instance
- **Expected:**
  - `post_id` matches input
  - `liked_by` matches input
  - `id` is a valid UUID
  - `created_at` is set
- **Last Verified:** 2026-05-10

#### TC-UNIT-827: Post entity — like_count default 0
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_post_entity.py::TestPostEntity::test_like_count_defaults_to_zero`
- **Preconditions:** — 
- **Steps:** Create Post via `Post.create()`
- **Expected:** `post.like_count == 0`
- **Last Verified:** 2026-05-10

## API Test Cases

#### TC-API-114: Like Post — authenticated toggle on
- **Type:** Positive
- **Layer:** API
- **File:** `api/test_likes.py::TestLikePost::test_like_post_authenticated`
- **Preconditions:** Post exists, user authenticated
- **Steps:** POST `/api/v1/posts/{id}/like` with auth header
- **Expected:**
  - Status 200
  - `like_count == 1`
- **Last Verified:** 2026-05-10

#### TC-API-115: Like Post — authenticated toggle off
- **Type:** Positive
- **Layer:** API
- **File:** `api/test_likes.py::TestLikePost::test_unlike_post_authenticated`
- **Preconditions:** Post exists, user already liked it
- **Steps:** POST `/api/v1/posts/{id}/like` second time
- **Expected:**
  - Status 200
  - `like_count == 0`
- **Last Verified:** 2026-05-10

#### TC-API-116: Like Post — guest via device_id
- **Type:** Positive
- **Layer:** API
- **File:** `api/test_likes.py::TestLikePost::test_like_post_as_guest`
- **Preconditions:** Post exists, guest token used
- **Steps:** POST `/api/v1/posts/{id}/like` with guest token
- **Expected:**
  - Status 200
  - `like_count == 1`
- **Last Verified:** 2026-05-10

#### TC-API-117: Like Post — not found
- **Type:** Negative
- **Layer:** API
- **File:** `api/test_likes.py::TestLikePost::test_like_post_not_found`
- **Preconditions:** Post does not exist
- **Steps:** POST `/api/v1/posts/{id}/like` with auth header
- **Expected:**
  - Status 404
- **Last Verified:** 2026-05-10

## Web Test Cases

#### TC-WEB-001: Like count on post list
- **Type:** Positive
- **Layer:** Web
- **File:** `tests/web/test_likes.py::TestLikeDisplay::test_like_count_on_homepage`
- **Preconditions:** Posts exist with known like counts
- **Steps:** GET `/web/`
- **Expected:**
  - Each post card shows like count
  - `data-testid="like-count-{post.id}"` present
- **Last Verified:** 2026-05-10

#### TC-WEB-002: Like button on post detail
- **Type:** Positive
- **Layer:** Web
- **File:** `tests/web/test_likes.py::TestLikeDisplay::test_like_button_on_detail`
- **Preconditions:** Post exists
- **Steps:** GET `/web/posts/{slug}`
- **Expected:**
  - Like count displayed
  - `data-testid="like-button"` present
- **Last Verified:** 2026-05-10

#### TC-WEB-003: Like toggle via POST
- **Type:** Positive
- **Layer:** Web
- **File:** `tests/web/test_likes.py::TestLikeToggle::test_like_toggle_via_web`
- **Preconditions:** Post exists
- **Steps:** POST `/web/posts/{slug}/like` redirects back
- **Expected:**
  - 303 redirect to post detail
  - Like count incremented
- **Last Verified:** 2026-05-10

## E2E Test Cases

#### TC-E2E-106: Like/Unlike flow via web UI
- **Type:** Positive
- **Layer:** E2E
- **File:** `tests/e2e/test_likes.py::test_like_unlike_flow`
- **Scenario:** Create post → like → verify count → unlike → verify count
- **Expected:** Count toggles correctly (0→1→0)
- **Last Verified:** 2026-05-10

#### TC-E2E-107: Separate users can both like
- **Type:** Positive
- **Layer:** E2E
- **File:** `tests/e2e/test_likes.py::test_multiple_users_can_like`
- **Scenario:** User1 likes → count=1 → User2 likes → count=2
- **Expected:** Count increments per user
- **Last Verified:** 2026-05-10

#### TC-E2E-108: Guest redirect on like
- **Type:** Positive
- **Layer:** E2E
- **File:** `tests/e2e/test_likes.py::test_guest_redirect_on_like`
- **Scenario:** Guest opens published post → clicks like → redirected to login
- **Expected:** 401 redirects to `/auth/dev-login`
- **Last Verified:** 2026-05-10

## Coverage Summary

| Component | Cases | Status |
|-----------|-------|--------|
| TogglePostLikeUseCase | 5 | ✅ Verified |
| Domain Entities (PostLike, Post) | 2 | ✅ Verified |
| API Endpoints | 4 | ✅ Verified |
| Web Display | 3 | ⬜ Planned |
| E2E Flows | 3 | ✅ Verified |

## Gaps (Not Yet Covered)

- [ ] Web tests (TC-WEB-001–003) — test infrastructure pending
- [ ] Full device_id middleware for guest like support