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

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.