Chapter 36: Testing Web Applications

FastAPI testing uses a test client for HTTP-level tests and dependency overrides for test seams.

from fastapi.testclient import TestClient

from recipevault.main import app


client = TestClient(app)


def test_health_endpoint():
    response = client.get("/health")
    assert response.status_code == 200
    assert response.json() == {"status": "ok"}

Dependency override:

def override_current_user():
    return User(id=1, email="admin@example.com", roles=["admin"])


app.dependency_overrides[get_current_user] = override_current_user

Integration test levels:

• Route test with fake dependencies.
• Route test with real database transaction.
• Repository test against test database.
• Browser-level test with Playwright if the UI becomes important.
• Contract test for OpenAPI schema.

For database tests, prefer isolated transactions, test containers, or a dedicated test database. SQLite is useful, but it is not a perfect substitute for PostgreSQL behavior.