The Complete Production SOP: How to Deploy and Run pytest Fixtures, Parametrization & Mock Testing in Autonomous AI Agents

---
name: "pytest-fixtures-parametrization"
description: "Write comprehensive, clean Python test suites using pytest fixtures and test matrices."
metadata:
  author: "pytest-dev"
  version: "1.0.0"
  runtime_compatibility:
    - "codex"
    - "claude-code"
    - "cursor"
    - "windsurf"
triggers:
  - "write pytest fixture"
  - "parametrize test pytest"
  - "async test pytest-asyncio"
permissions:
  fs_read: true
  fs_write: "workspace"
  shell_exec: false
  net_access: false
---

[tool.pytest.ini_options]
minversion = "8.0"
addopts = "-ra -q --strict-markers --cov=app --cov-report=term-missing"
testpaths = ["tests"]
asyncio_mode = "auto"
asyncio_default_fixture_loop_scope = "function"
markers = [
    "slow: marks tests as slow (deselect with '-m \"not slow\"')",
    "integration: marks integration tests requiring mocked external services",
]

import pytest
from typing import AsyncGenerator, Generator
from unittest.mock import AsyncMock, MagicMock

@pytest.fixture(scope="session")
def app_config() -> dict[str, str]:
    """Immutable session-scoped configuration fixture."""
    return {"ENV": "test", "DB_URL": "sqlite+aiosqlite:///:memory:"}

@pytest.fixture(scope="function")
def mock_stripe_client() -> Generator[MagicMock, None, None]:
    """Yield-based mock client ensuring post-test cleanup."""
    client = MagicMock()
    client.charges.create.return_value = {"id": "ch_test_123", "status": "succeeded"}
    yield client
    client.reset_mock()

@pytest.fixture(scope="function")
async def async_db_session() -> AsyncGenerator[AsyncMock, None]:
    """Async fixture with deterministic setup and teardown."""
    session = AsyncMock()
    session.is_active = True
    yield session
    await session.close()

import pytest
from app.billing import calculate_discounted_price

@pytest.mark.parametrize(
    "base_price,discount_tier,expected_final_price",
    [
        (100.0, "standard", 100.0),
        (100.0, "bronze", 95.0),
        (100.0, "silver", 85.0),
        (100.0, "gold", 75.0),
        (0.0, "gold", 0.0),
    ],
    ids=["tier-standard", "tier-bronze", "tier-silver", "tier-gold", "tier-zero-base"],
)
def test_pricing_matrix_discounts(base_price: float, discount_tier: str, expected_final_price: float):
    result = calculate_discounted_price(base_price, discount_tier)
    assert result == pytest.approx(expected_final_price, rel=1e-3)

@pytest.mark.parametrize(
    "invalid_price,invalid_tier,expected_exception",
    [
        (-10.0, "gold", ValueError),
        (100.0, "platinum_nonexistent", KeyError),
    ],
)
def test_pricing_matrix_exceptions(invalid_price: float, invalid_tier: str, expected_exception: type[Exception]):
    with pytest.raises(expected_exception):
        calculate_discounted_price(invalid_price, invalid_tier)