rules-testinglisted

### 1. Principle Tests assert behaviour at the package boundary, not internal implementation. A refactor that preserves behaviour must not require test changes. - **Integration** = default. Real dependencies via Docker. - **Unit** = fallback when the unit has no outside world (VO, pure formatter, parser without I/O). - Unit test needing 3+ Mocks = bad Integration test in disguise. ### 2. Rules | Concern | Rule | |---|---| | Mapping | `src/Cache/RedisCache.php` → `tests/Integration/Cache/RedisCacheTest.php` | | Naming | Class `RedisCacheTest`, method `test{Action}{Condition}{ExpectedResult}` | | Structure | AAA separated, one concept per test | | Independence | No `setUpBeforeClass` side effects, no static cache, no `@depends` | | Behaviour | Assert outputs and side effects, never SQL strings or private calls | | Mocking | Only Contracts (interfaces). Prefer Fakes in `tests/Support/` | ```php // tests/Support/InMemoryCache.php final class InMemoryCache implements CacheInterface { private array $data = []; public function get(string $key, mixed $default = null): mixed { return $this->data[$key] ?? $default; } public function set(string $key, mixed $value, int|null $ttl = null): bool { $this->data[$key] = $value; return true; } } ``` ### 3. Failing-test process Before changing test or code: 1. What SHOULD happen? Derive from architecture, PRD, Contract. 2. What ACTUALLY happens? Debug output, read involved code. 3. Decide: - Behaviour correct → adapt test,