test:mock

Command /test:mock

Create a mock for an external dependency in tests.

When to Use Mocks

• External services — email, SMS, payment gateways
• Network requests — HTTP clients, API calls
• File system — file read/write operations
• Time — datetime.now(), time.sleep()
• Random values — random, uuid

Do NOT Mock

• Code under test — pointless
• Simple functions — if you can use real ones
• Database — better to use a test database with rollback

Instructions

Step 1: Identify what to mock

Find the dependency in code:

# src/modules/users/services.py
class UserService:
    def __init__(self, email_service: EmailService) -> None:
        self._email = email_service

    async def register(self, data: UserCreate) -> User:
        user = await self._repo.create(data)
        await self._email.send_welcome(user.email)  # ← this needs to be mocked
        return user

Step 2: Create the mock

Mock Examples

AsyncMock for async dependencies

import pytest
from unittest.mock import AsyncMock


@pytest.fixture
def mock_email_service() -> AsyncMock:
    """Mock email service."""
    mock = AsyncMock()
    mock.send_welcome.return_value = True
    mock.send_reset_password.return_value = True
    return mock


# Usage
async def test_register_sends_welcome_email(
    mock_email_service: AsyncMock,
) -> None:
    service = UserService(email_service=mock_email_service)

    await service.register({"email": "[email protected]"})

    mock_email_service.send_welcome.assert_called_once_with("[email protected]")

MagicMock for sync dependencies

from unittest.mock import MagicMock


@pytest.fixture
def mock_cache() -> MagicMock:
    """Mock cache."""
    mock = MagicMock()
    mock.get.return_value = None
    mock.set.return_value = True
    mock.delete.return_value = True
    return mock

patch for module-level replacement

from unittest.mock import patch, AsyncMock


async def test_external_api_call():
    with patch(
        "src.modules.orders.services.httpx.AsyncClient.post",
        new_callable=AsyncMock,
    ) as mock_post:
        mock_post.return_value.status_code = 200
        mock_post.return_value.json.return_value = {"success": True}

        result = await order_service.create_payment(order_id=1)

        assert result["success"] is True
        mock_post.assert_called_once()