Backend Tests (pytest + anyio)

Tests live in backend/tests/, mirror the source layout (app/services/user.py → tests/services/test_user.py), and run with no real database — conftest.py overrides get_db_session with an AsyncMock via FastAPI dependency_overrides.

Key fixtures (tests/conftest.py)

• client — httpx.AsyncClient over ASGITransport(app=app) (use this, not Starlette TestClient)
• mock_db_session — AsyncMock standing in for AsyncSession
• mock_redis (when Redis is enabled), api_key_headers (when API keys are enabled)

Patterns

Async tests use anyio, not @pytest.mark.asyncio:

import pytest

pytestmark = pytest.mark.anyio  # at module top, or mark per-test

Service test — stub what the repo/session returns, assert behavior + exceptions:

async def test_get_user_not_found_raises(monkeypatch, mock_db_session):
    service = UserService(mock_db_session)
    monkeypatch.setattr(user_repo, "get_by_id", AsyncMock(return_value=None))
    with pytest.raises(NotFoundError):
        await service.get_by_id(UUID("00000000-0000-0000-0000-000000000000"))

API test — drive the route through client, override auth deps with a mock user:

async def test_create_user_returns_201(client: AsyncClient):
    app.dependency_overrides[get_current_user] = lambda: mock_user
    resp = await client.post("/api/v1/users", json={"email": "a@b.com", "password": "secret123"})
    assert resp.status_code == 201

Naming & rules

• test_<action>_<scenario>_<expected_result> (e.g. test_create_user_with_duplicate_email_raises_already_exists_error)
• One behavior per test; plain assert (pytest rewrites it)
• Use factory fixtures for data, not raw dicts; each test independent
• Clear app.dependency_overrides after the test (the client fixture already does this for the DB/Redis overrides)

Run

cd backend && uv run pytest                 # all
uv run pytest tests/services/test_user.py -v
uv run pytest --cov=app                      # coverage

After writing tests, run uv run ruff check . --fix && uv run ruff format . and confirm uv run pytest is green.