Mode d’emploi
- Copiez la commande et examinez le paquet avant de l’installer dans votre environnement agent.
- Consultez le document original pour les outils, identifiants et environnements requis.
- Décrivez les entrées et le livrable souhaité ; comparez la sortie aux sources.
npx skills add https://github.com/lambdatest/agent-skills --skill pytest-skillAvant de commencer
- L’installation n’inclut ni abonnement au modèle, ni quota API, ni accès aux fichiers.
- Étoiles et installations reflètent l’activité, pas un test indépendant de qualité ou de sécurité.
Document Skill original
Rendu depuis le dépôt source en conservant titres, exemples, code, tableaux, liens et images.
Pytest Testing Skill
Core Patterns
Basic Test
python
import pytest
def test_addition():
assert 2 + 3 == 5
def test_exception():
with pytest.raises(ValueError, match="invalid"):
int("not_a_number")
class TestCalculator:
def test_add(self):
calc = Calculator()
assert calc.add(2, 3) == 5
def test_divide_by_zero(self):
with pytest.raises(ZeroDivisionError):
Calculator().divide(10, 0)Fixtures
python
@pytest.fixture
def calculator():
return Calculator()
@pytest.fixture
def db_connection():
conn = Database.connect("test_db")
yield conn # teardown after yield
conn.rollback()
conn.close()
@pytest.fixture(scope="module")
def api_client():
client = APIClient(base_url="http://localhost:8000")
yield client
client.logout()
# conftest.py - shared fixtures
@pytest.fixture(autouse=True)
def reset_state():
State.reset()
yield
State.cleanup()
# Usage
def test_add(calculator):
assert calculator.add(2, 3) == 5Parametrize
python
@pytest.mark.parametrize("input,expected", [
("hello", 5), ("", 0), ("pytest", 6),
])
def test_string_length(input, expected):
assert len(input) == expected
@pytest.mark.parametrize("a,b,expected", [
(2, 3, 5), (-1, 1, 0), (0, 0, 0),
])
def test_add(calculator, a, b, expected):
assert calculator.add(a, b) == expectedMarkers
python
@pytest.mark.slow
def test_large_dataset(): ...
@pytest.mark.skip(reason="Not implemented")
def test_future_feature(): ...
@pytest.mark.skipif(sys.platform == "win32", reason="Unix only")
def test_unix_permissions(): ...
@pytest.mark.xfail(reason="Known bug #123")
def test_known_bug(): ...Mocking
python
from unittest.mock import patch, MagicMock
def test_send_email(mocker):
mock_smtp = mocker.patch("myapp.email.smtplib.SMTP")
send_welcome_email("user@test.com")
mock_smtp.return_value.sendmail.assert_called_once()
def test_api_call(mocker):
mock_response = mocker.Mock()
mock_response.status_code = 200
mock_response.json.return_value = {"users": [{"name": "Alice"}]}
mocker.patch("myapp.service.requests.get", return_value=mock_response)
users = get_users()
assert len(users) == 1
@patch("myapp.service.database")
def test_save_user(mock_db):
mock_db.save.return_value = True
assert save_user({"name": "Alice"}) is True
mock_db.save.assert_called_once()Assertions
python
assert x == y
assert x != y
assert x in collection
assert isinstance(obj, MyClass)
assert 0.1 + 0.2 == pytest.approx(0.3)
with pytest.raises(ValueError) as exc_info:
raise ValueError("bad")
assert "bad" in str(exc_info.value)Anti-Patterns
| Bad | Good | Why |
|---|---|---|
self.assertEqual() | assert x == y | pytest rewrites give better output |
Setup in __init__ | @pytest.fixture | Lifecycle management |
| Global state | Fixture with yield | Proper cleanup |
| Huge test functions | Small focused tests | Easier debugging |
Quick Reference
| Task | Command |
|---|---|
| Run all | pytest |
| Run file | pytest tests/test_login.py |
| Run specific | pytest tests/test_login.py::test_login_success |
| By marker | pytest -m slow |
| By keyword | pytest -k "login and not invalid" |
| Verbose | pytest -v |
| Stop first fail | pytest -x |
| Last failed | pytest --lf |
| Coverage | pytest --cov=myapp --cov-report=html |
| Parallel | pytest -n auto (pytest-xdist) |
pyproject.toml
toml
[tool.pytest.ini_options]
testpaths = ["tests"]
markers = ["slow: slow tests", "integration: integration tests"]
addopts = "-v --tb=short"Deep Patterns
For production-grade patterns, see reference/playbook.md:
| Section | What's Inside |
|---|---|
| §1 Config | pytest.ini + pyproject.toml with markers, coverage |
| §2 Fixtures | Scoping, factories, teardown, autouse, tmp_path |
| §3 Parametrize | Basic, with IDs, cartesian, indirect |
| §4 Mocking | pytest-mock, monkeypatch, spies, env vars |
| §5 Async | pytest-asyncio, async fixtures, async client |
| §6 Exceptions | pytest.raises(match=), warnings |
| §7 Markers & Plugins | Custom markers, collection hooks |
| §8 Class-Based | Nested classes, autouse setup |
| §9 CI/CD | GitHub Actions matrix, coverage gates |
| §10 Debugging Table | 10 common problems with fixes |
| §11 Best Practices | 15-item production checklist |
