Leanpub Header

Skip to main content
Go to Leanpub.com

Testing Rails from Scratch

A practical, (mostly) out-of-the-box approach to test-driven development in Ruby on Rails

This book is 20% completeLast updated on 2026-06-27
Aaron Sumner

Real-world advice for adding reliable tests to your Rails apps with the default tools (mostly), complete with expanded, exclusive content and a full sample application. Learn to test with confidence!

Minimum price

$19.00

$29.00

You pay

Author earns

$

Also available for 1 book credit with a Reader Membership

PDF
EPUB
WEB
APP
40
Pages
About

About

About the Book

Ruby on Rails offers powerful tools to test your software's features out of the box. But how do you use them to ship code with confidence? And how do you ensure that AI-generated code works as intended?

Testing Rails from Scratch is a practical guide to testing Rails applications at every level, using (mostly) tools that the framework includes by default. You'll learn to test the way I did, by starting with simple building blocks and expanding into complex tests covering broad swaths of your code. Learn to test with confidence!

Testing Rails from Scratch covers Ruby on Rails 8.1 and Ruby 4.0.

Share this book

Categories

SoftwareTestingAutomated Software TestingRuby on RailsWeb Development

Feedback

Email the Author

Author

About the Author

Aaron Sumner

Aaron Sumner is a software developer and educator who has helped thousands of programmers level up their software engineering skills. In his blog, Left of the Dev, Aaron shows how to be a productive developer, even when time and other resources are tight.

The Leanpub Podcast

Episode 154

An Interview with Aaron Sumner

Launch

Launch Video

Subscribe on YouTube

Clips

Clips

View all clips →

Contents

Table of Contents

1. Introduction

  1. Confident testing
  2. Why Minitest?
  3. Who should read this book
  4. My testing philosophy
  5. How the book is organized
  6. Downloading the sample code
  7. Code conventions
  8. Discussion and errata
  9. A note about gem versions
  10. A note about styling
  11. About the sample application

2. Setting up Minitest

  1. Test database
  2. Clean the slate
  3. Nicer reporting
  4. Summary
  5. Exercises

3. Model tests

  1. Anatomy of a model test
  2. Creating a model test
  3. An aside on test
  4. More Minitest syntax
  5. Testing validations
  6. Testing instance methods
  7. Testing class methods and scopes
  8. Testing all the cases
  9. Summary
  10. Exercises

About Left of the Dev

About the author

Colophon

The Leanpub 60 Day 100% Happiness Guarantee

Within 60 days of purchase you can get a 100% refund on any Leanpub purchase, in two clicks.

See full terms...

Earn $8 on a $10 Purchase, and $16 on a $20 Purchase

We pay 80% royalties on purchases of $7.99 or more, and 80% royalties minus a 50 cent flat fee on purchases between $0.99 and $7.98. You earn $8 on a $10 sale, and $16 on a $20 sale. So, if we sell 5000 non-refunded copies of your book for $20, you'll earn $80,000.

(Yes, some authors have already earned much more than that on Leanpub.)

In fact, authors have earned over $15 million writing, publishing and selling on Leanpub.

Learn more about writing on Leanpub

Free Updates. DRM Free.

If you buy a Leanpub book, you get free updates for as long as the author updates the book! Many authors use Leanpub to publish their books in-progress, while they are writing them. All readers get free updates, regardless of when they bought the book or how much they paid (including free).

Most Leanpub books are available in PDF (for computers) and EPUB (for phones, tablets and Kindle). The formats that a book includes are shown at the top right corner of this page.

Finally, Leanpub books don't have any DRM copy-protection nonsense, so you can easily read them on any supported device.

Learn more about Leanpub's ebook formats and where to read them

Write and Publish on Leanpub

You can use Leanpub to easily write, publish and sell in-progress and completed ebooks and online courses!

Leanpub is a powerful platform for serious authors, combining a simple, elegant writing and publishing workflow with a store focused on selling in-progress ebooks.

Leanpub is a magical typewriter for authors: just write in plain text, and to publish your ebook, just click a button. (Or, if you are producing your ebook your own way, you can even upload your own PDF and/or EPUB files and then publish with one click!) It really is that easy.

Learn more about writing on Leanpub