pytest-skill

Files (3)

• SKILL.md
• advanced-patterns.md · reference/
• playbook.md · reference/

SKILL.md (first lines)

# 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) == 5
```

### Parametrize

```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) == expected
```

### Markers

```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

From LambdaTest/agent-skills, MIT.

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