# Test Model: Domain Foundation

Feature: Core domain building blocks — entities, value objects, and exceptions.
These tests validate business rules at the domain layer with no external dependencies.

## Unit Test Cases

### Entities

#### TC-UNIT-201: Post Creation
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_entities.py::TestPost::test_post_creation`
- **Expected:**
  - `id` is a valid UUID
  - `title.value == "Test Title"`
  - `content.value` matches input
  - `slug.value == "test-title"` (auto-generated)
  - `author_id == "user-123"`
  - `published is False`
  - `tags == ["test", "python"]`
- **Last Verified:** 2026-05-07

#### TC-UNIT-202: Post Publish
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_entities.py::TestPost::test_post_publish`
- **Expected:** `published` transitions from `False` to `True`
- **Last Verified:** 2026-05-07

#### TC-UNIT-203: Post Unpublish
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_entities.py::TestPost::test_post_unpublish`
- **Expected:** `published` transitions from `True` to `False`
- **Last Verified:** 2026-05-07

#### TC-UNIT-204: Post Update Title
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_entities.py::TestPost::test_post_update_title`
- **Expected:** Title and slug updated, `updated_at` changed
- **Last Verified:** 2026-05-07

#### TC-UNIT-205: Post Update Content
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_entities.py::TestPost::test_post_update_content`
- **Expected:** Content updated, `updated_at` changed
- **Last Verified:** 2026-05-07

#### TC-UNIT-206: Post Update Tags
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_entities.py::TestPost::test_post_update_tags`
- **Expected:** Tags replaced with new list, `updated_at` changed
- **Last Verified:** 2026-05-07

#### TC-UNIT-207: Post Add Tag
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_entities.py::TestPost::test_post_add_tag`
- **Expected:** New tag appended to existing tags
- **Last Verified:** 2026-05-07

#### TC-UNIT-208: Post Remove Tag
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_entities.py::TestPost::test_post_remove_tag`
- **Expected:** Tag removed from list
- **Last Verified:** 2026-05-07

### Value Objects

#### TC-UNIT-301: Title — Valid
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestTitle::test_valid_title`
- **Expected:** `Title("Valid Title").value == "Valid Title"`
- **Last Verified:** 2026-05-07

#### TC-UNIT-302: Title — Too Short
- **Type:** Negative
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestTitle::test_title_too_short`
- **Expected:** Raises `ValueError` with message containing "at least"
- **Last Verified:** 2026-05-07

#### TC-UNIT-303: Title — Too Long
- **Type:** Negative
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestTitle::test_title_too_long`
- **Expected:** Raises `ValueError` with message containing "at most"
- **Last Verified:** 2026-05-07

#### TC-UNIT-304: Title — Empty / Whitespace
- **Type:** Negative
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestTitle::test_title_empty`
- **Expected:** Raises `ValueError` with message containing "empty"
- **Last Verified:** 2026-05-07

#### TC-UNIT-305: Title — Non-String
- **Type:** Negative
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestTitle::test_title_not_string`
- **Expected:** Raises `ValueError` with message containing "string"
- **Last Verified:** 2026-05-07

#### TC-UNIT-306: Content — Valid
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestContent::test_valid_content`
- **Expected:** Content created successfully
- **Last Verified:** 2026-05-07

#### TC-UNIT-307: Content — Too Short
- **Type:** Negative
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestContent::test_content_too_short`
- **Expected:** Raises `ValueError` with "at least"
- **Last Verified:** 2026-05-07

#### TC-UNIT-308: Content — Too Long
- **Type:** Negative
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestContent::test_content_too_long`
- **Expected:** Raises `ValueError` with "at most"
- **Last Verified:** 2026-05-07

#### TC-UNIT-309: Content — Empty / Whitespace
- **Type:** Negative
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestContent::test_content_empty`
- **Expected:** Raises `ValueError` with "empty"
- **Last Verified:** 2026-05-07

#### TC-UNIT-310: Slug — Valid
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestSlug::test_valid_slug`
- **Expected:** `Slug("valid-slug").value == "valid-slug"`
- **Last Verified:** 2026-05-07

#### TC-UNIT-311: Slug — From Title
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestSlug::test_slug_from_title`
- **Expected:** `Slug.from_title("Hello World Post") == "hello-world-post"`
- **Last Verified:** 2026-05-07

#### TC-UNIT-312: Slug — From Title with Special Characters
- **Type:** Edge
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestSlug::test_slug_from_title_with_special_chars`
- **Expected:** Special chars stripped, words hyphenated
- **Last Verified:** 2026-05-07

#### TC-UNIT-313: Slug — From Title with Only Special Characters
- **Type:** Edge
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestSlug::test_slug_from_title_only_special_chars`
- **Expected:** Falls back to `"post"`
- **Last Verified:** 2026-05-07

#### TC-UNIT-314: Slug — Invalid Characters (underscore)
- **Type:** Negative
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestSlug::test_slug_invalid_chars`
- **Expected:** Raises `ValueError` with "lowercase"
- **Last Verified:** 2026-05-07

#### TC-UNIT-315: Slug — Uppercase Letters
- **Type:** Negative
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestSlug::test_slug_uppercase`
- **Expected:** Raises `ValueError` with "lowercase"
- **Last Verified:** 2026-05-07

#### TC-UNIT-316: Slug — Equality and Hash
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_value_objects.py::TestSlug::test_slug_equality`
- **Expected:** Equal slugs have equal values and hashes
- **Last Verified:** 2026-05-07

### Exceptions

#### TC-UNIT-401: DomainException — Base
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_exceptions.py::TestDomainExceptions::test_base_exception`
- **Expected:** Message stored and returned via `str()`
- **Last Verified:** 2026-05-07

#### TC-UNIT-402: ValidationException
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_exceptions.py::TestDomainExceptions::test_validation_exception`
- **Expected:** Inherits `DomainException`, stores message
- **Last Verified:** 2026-05-07

#### TC-UNIT-403: NotFoundException
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_exceptions.py::TestDomainExceptions::test_not_found_exception`
- **Expected:** Inherits `DomainException`, stores message
- **Last Verified:** 2026-05-07

#### TC-UNIT-404: AlreadyExistsException
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_exceptions.py::TestDomainExceptions::test_already_exists_exception`
- **Expected:** Inherits `DomainException`, stores message
- **Last Verified:** 2026-05-07

#### TC-UNIT-405: UnauthorizedException
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_exceptions.py::TestDomainExceptions::test_unauthorized_exception`
- **Expected:** Inherits `DomainException`, stores message
- **Last Verified:** 2026-05-07

#### TC-UNIT-406: ForbiddenException
- **Type:** Positive
- **Layer:** Unit
- **File:** `unit/domain/test_exceptions.py::TestDomainExceptions::test_forbidden_exception`
- **Expected:** Inherits `DomainException`, stores message
- **Last Verified:** 2026-05-07

## Coverage Summary

| Component | Cases | Status |
|-----------|-------|--------|
| Post Entity | 8 | ✅ All core operations covered |
| Title VO | 5 | ✅ Validation rules fully covered |
| Content VO | 4 | ✅ Validation rules fully covered |
| Slug VO | 7 | ✅ Generation and validation covered |
| Domain Exceptions | 6 | ✅ All exception types covered |

## Gaps (Not Yet Covered)

- [ ] TC-UNIT-209: Post Entity — `updated_at` does not change when update values are identical
- [ ] TC-UNIT-210: Post Entity — attempt to publish already published post (idempotent behavior)
- [ ] TC-UNIT-317: Slug — collision handling (unique constraint) at domain level
- [ ] TC-UNIT-318: Content — exact boundary values (min length - 1, max length + 1)