pytest-service

Skill: pytest-service

Core position

This skill establishes clean, reliable backend testing using pytest.

The goal is to produce tests that are:

• fast
• deterministic
• easy to read
• easy to extend
• free of infrastructure dependencies

Tests should optimize for scanability and maintainability, not clever abstractions.

Core testing stance

Prefer simple local tests with minimal infrastructure.

Rules:

• Use httpx.AsyncClient with ASGITransport for FastAPI endpoint tests
• All test functions are async def; asyncio_mode = "auto" eliminates per-test markers
• Use pytest_asyncio fixtures for async setup/teardown
• Default test databases to async SQLite via SQLAlchemy async fixtures
• Do not introduce Docker databases unless the repository already uses them for testing
• External clients must be mocked, not called
• No test classes — top-level test_* functions only; fixtures handle all setup
• Each test covers a distinct behavior — no redundant assertions across tests
• Avoid mutable default arguments in fixtures and helpers
• Dev deps assumed: pytest, pytest-asyncio, httpx

Tests must run reliably with a simple pytest. No external services required.

Project structure

Tests should live in a tests/ directory.

tests/
  conftest.py
  test_health.py
  test_users.py
  factories/
    user_factory.py

• conftest.py holds shared fixtures
• test files mirror application modules when possible
• factory fixtures may live in tests/factories/ or conftest.py

Fixture discipline

Shared setup belongs in pytest fixtures, not duplicated code.

• Use @pytest.fixture for reusable setup
• Inspect existing fixtures before creating new ones
• Prefer composing fixtures instead of duplicating setup logic
• Keep fixture responsibilities narrow and clearly named

Avoid inline setup repeated across tests.

Fixture scope