## ADDED Requirements

### Requirement: Shared Test Fixtures

The system SHALL provide shared fixtures in `conftest.py` for common test needs.

#### Scenario: Database session fixture
- GIVEN an integration test
- WHEN using the `db_session` fixture
- THEN it SHALL provide an async SQLAlchemy session
- AND the session SHALL use transaction rollback for isolation

#### Scenario: Test client fixture
- GIVEN an API integration test
- WHEN using the `client` fixture
- THEN it SHALL provide an authenticated TestClient instance
- AND the client SHALL have valid access and refresh tokens

#### Scenario: SQLite unit test database
- GIVEN a unit test
- WHEN the test uses the `db_engine` fixture
- THEN it SHALL provide an in-memory SQLite engine
- AND no PostgreSQL connection SHALL be required

### Requirement: Transaction Isolation

The system SHALL ensure integration tests don't pollute the database.

#### Scenario: Rollback after test
- GIVEN an integration test creates data
- WHEN the test completes
- THEN all database changes SHALL be rolled back
- AND subsequent tests SHALL see a clean database state

#### Scenario: Parallel test safety
- GIVEN multiple integration tests run concurrently
- WHEN each test uses transaction isolation
- THEN tests SHALL not interfere with each other