# Test Execution

Prerequisites:
- Backend API running at `BASE_URL` (default `http://127.0.0.1:8000`)
- PostgreSQL reachable via `DB_DSN`

Environment:
- `BASE_URL` (optional)
- `DB_DSN` (optional)

Install deps:

```
pip install pytest requests psycopg2-binary
```

Run all tests:

```
pytest -q
```

Run a subset:

```
pytest -q tests/db_invariants
pytest -q tests/e2e_api
pytest -q tests/e2e_engine
pytest -q tests/concurrency
pytest -q tests/failure_injection
```