Test-Driven Development with Python

The third edition of this trusted guide demonstrates the practical advantages of test-driven development (TDD) with Python and describes how to develop a real web application. You’ll learn how to write and run tests before building each part of your app and then develop the minimum amount of code required to pass those tests. The result? Clean code that works.

In the process, author Harry Percival teaches software and web developers the basics of Django, Selenium, Git, JavaScript, and Mock libraries, along with current web development techniques. This book–updated for Python 3.11 and Django 4–clearly demonstrates how TDD encourages simple designs and inspires confidence.

Fully updated, this third edition addresses:

• The TDD workflow, including the unit test/code cycle and refactoring
• Unit tests for classes and functions and functional tests for user interactions within the browser
• Mock objects and the pros and cons of isolated versus integrated tests
• Testing and automation of deployments with a staging server
• Tests applied to the third-party plug-ins you integrate into your site
• Automatic tests using a continuous integration environment
• Using TDD to build a REST API with a JavaScript frontend interface

Table of Contents

Part I. The Basics of TDD and Django

Chapter 1. Getting Django Set Up Using a Functional Test

Chapter 2. Extending Our Functional Test Using the unittest Module

Chapter 3. Testing a Simple Home Page with Unit Tests

Chapter 4. What Are We Doing with All lhese Tests? (And, Refactoring)

Chapter 5. Saving User Input: Testing the Database

Chapter 6. Improving Functional Tests: Ensuring Isolation and Removing Magic Sleeps

Chapter 7. Working Incrementally

Chapter 8. Prettification: Layout and Styling, and What to Test About It

Part II. Going to Production

Chapter 9. Containerization aka Docker

Chapter 10. Making Our App Production-Ready

Chapter 11. Getting a Server Ready for Deployment

Chapter 12. Infrastructure as Code: Automated Deployments with Ansible

Part Ill. Forms and Validation

Chapter 13. Splitting Our Tests into Multiple Files,

and a Generic Wait Helper

Chapter 14. Validation at the Database Layer

Chapter 15. A Simple Form

Chapter 16. More Advanced Forms

Part IV. More Advanced Topics in Testing

Chapter 17. A Gentle Excursion into JavaScript

Chapter 18. Deploying Our New Code

Chapter 19. User Authentication, Spiking, and De-Spiking

Chapter 20. Using Mocks to Test External Dependencies

Chapter 21. Using Mocks for Test Isolation

Chapter 22. Test Fixtures and a Decorator for Explicit Waits

Chapter 23. Debugging and Testing Server Issues

Chapter 24. Finishing “My Lists”: Outside-In TDD

Chapter 25. Cl: Continuous Integration

Chapter 26. The Token Social Bit, the Page Pattern, and an Exercise for the Reader

Chapter 27. Fast Tests, Slow Tests, and Hot Lava

About the Author

After an idyllic childhood spent playing with BASIC on French 8-bit computers like the Thomson T-07 whose keys go “boop” when you press them, Harry spent a few years being deeply unhappy as a management consultant. Soon he rediscovered his true geek nature, and was lucky enough to fall in with a bunch of XP fanatics, working on the pioneering but sadly defunct Resolver One spreadsheet. He now works at PythonAnywhere LLP, and spreads the gospel of TDD world-wide at talks, workshops and conferences, with all the passion and enthusiasm of a recent convert.