Kent Beck's foundational work on TDD that introduced the methodology of writing tests before code. This seminal book demonstrates TDD through practical examples including a multi-currency system and building a testing framework from scratch.

This is the book that started it all. Kent Beck's Test-Driven Development: By Example isn't just a book about testing—it's a manifesto for how to think about software development. Beck introduces TDD not as a technique, but as a way to reduce fear in programming. When you write tests first, you're not just verifying code works; you're designing the interface, clarifying requirements, and building confidence incrementally. The book is structured in three parts: The Money Example walks you through building a multi-currency system step-by-step, showing how tests drive design decisions. The xUnit Example is brilliant—you build a testing framework using TDD itself, which teaches you both how to write tests and how testing frameworks work under the hood. The Patterns section distills the lessons into reusable practices. What makes this book timeless is that it's not about tools or languages—it's about the rhythm of red-green-refactor, the discipline of writing failing tests first, and the confidence that comes from knowing your code works because you've proven it. In the age of AI code assistants, this book becomes even more critical: when AI generates code, TDD ensures you're not just accepting what it produces—you're verifying it meets your actual requirements. The examples are in Java, but the principles apply to any language. This is required reading for any serious developer.

Kent Beck's foundational TDD book that introduced test-first development. Learn the red-green-refactor rhythm through practical examples.

Test-Driven Development: By Example - Kent Beck Book Review

Test-Driven Development: By Example

Roy Osherove's concrete patterns and habits for writing useful tests, not just more tests. Learn how to write tests that actually help you, not just satisfy coverage metrics.

The Art of Unit Testing is the book that taught me the difference between tests that help and tests that just exist. Osherove's third edition updates the examples for JavaScript, but the principles are timeless. The chapter on test structure—arrange, act, assert—gave me a framework for writing readable tests, and the section on mocks and stubs helped me understand when to use each. The book's focus on test quality over quantity resonated: I'd been writing tests that passed but didn't catch bugs, and Osherove shows why. The chapter on test maintainability helped me understand why some test suites are a joy to work with while others are a burden. My only critique is that some examples feel contrived, but the principles are sound. I've recommended it to developers who are writing tests but not getting value from them, and it's helped them see what they're missing. Essential reading for anyone who wants to write tests that actually help.

Roy Osherove's guide to writing useful tests, not just more tests. Learn concrete patterns and habits for test quality, maintainability, and when to use mocks.

The Art of Unit Testing: 3rd Edition with JavaScript

The Art of Unit Testing: with Examples in JavaScript (3rd Edition)

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Test-Driven Development: By Example

The Art of Unit Testing: with Examples in JavaScript (3rd Edition)