Testing Architecture

Test structure, fixtures, mocking strategies, and patterns.

Overview

Master test architecture.

Test Structure

# Project structure
# tests/
#   __init__.py
#   conftest.py
#   unit/
#     __init__.py
#     test_models.py
#     test_services.py
#   integration/
#     __init__.py
#     test_api.py
#     test_database.py

# conftest.py
import pytest
from myapp import create_app

@pytest.fixture
def app():
    app = create_app('testing')
    return app

@pytest.fixture
def client(app):
    return app.test_client()

@pytest.fixture
def db(app):
    with app.app_context():
        db.create_all()
        yield db
        db.drop_all()

Mocking Strategies

from unittest.mock import Mock, patch

# Mock at the import level
@patch('myapp.services.external_api')
def test_service(mock_api):
    mock_api.get.return_value.json.return_value = {"data": "test"}
    result = my_service.fetch_data()
    assert result["data"] == "test"

# Use fixture for common mocks
@pytest.fixture
def mock_db(monkeypatch):
    mock = Mock()
    monkeypatch.setattr('myapp.db.session', mock)
    return mock

Practice

Design a comprehensive test suite for a web application.