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Testing

SWEN has a layered test suite following the test pyramid: many fast unit tests, fewer slower integration tests, and a small number of external/manual tests.

Test Pyramid

          ┌──────────┐
          │ External │  ~5 tests — real bank connections (never in CI)
          ├──────────┤
          │  Integr. │  ~25% — Testcontainers, ephemeral PostgreSQL
          ├──────────────────────────┤
          │         Unit             │  ~70% — pure Python, all I/O mocked
          └──────────────────────────┘

Directory Structure

services/backend/tests/
├── swen/                    ← Main accounting domain
│   ├── unit/                ← Fast, isolated (no I/O)
│   └── integration/         ← Requires Postgres (Testcontainers)
├── swen_identity/           ← Identity/auth domain
│   ├── unit/
│   └── integration/
├── cross_domain/            ← Tests spanning multiple domains
│   ├── integration/
│   └── e2e/                 ← Full user journeys (bank connection, cash transactions)
├── external/                ← Real bank connections (manual only)
└── shared/                  ← Shared fixtures and utilities

Running Tests

make test
# or
uv run pytest services/backend/tests/ -v -m "not external and not manual"

uv run pytest services/backend/tests/ -v -m "not integration and not external"

uv run pytest services/backend/tests/ -v -m integration

make test-cov

Test Markers

Marker Meaning Runs in CI
@pytest.mark.integration Requires Postgres (Testcontainers) ✅ Yes
@pytest.mark.external Connects to a real bank ❌ Never
@pytest.mark.slow Long-running test ✅ Yes
@pytest.mark.manual Requires manual TAN input ❌ Never

Unit Tests

Unit tests have zero I/O — no database, no HTTP, no file system. All external dependencies are mocked with pytest-mock.

def test_transaction_must_balance():
    account = Account(...)
    with pytest.raises(DomainError, match="Transaction must balance"):
        Transaction.create(journal_entries=[...])  # unbalanced entries

Integration Tests — Testcontainers

Integration tests spin up an ephemeral PostgreSQL container per test session using Testcontainers. The container is destroyed after the session — no cleanup required, no shared state between runs.

@pytest.mark.integration
async def test_import_creates_bank_transactions(db_session):
    repo = BankTransactionRepository(db_session)
    # ... real DB calls against a fresh Postgres container

Podman Users

If you use Podman instead of Docker:

export DOCKER_HOST=unix:///run/user/$(id -u)/podman/podman.sock
export TESTCONTAINERS_RYUK_DISABLED=true

External Tests

Tests in tests/external/ connect to real FinTS banks. They require valid bank credentials:

export FINTS_BLZ=...
export FINTS_USERNAME=...
export FINTS_PIN=...

uv run pytest tests/external/ -v --run-external

These tests are never run in CI. Run them manually before a release if you want to validate bank connectivity.

CI Policy

Test type When runs
Unit Every push, every PR
Integration Every push, every PR
External Never automatically
Manual Never automatically

See CI / GitHub Actions for the full workflow breakdown.

ML Tests

make test-ml
# or
uv run pytest services/ml/tests/ -v

ML tests live in services/ml/tests/ and follow the same pyramid / marker conventions.