Learn how to build React apps using outside-in test-driven development, including end-to-end tests with Cypress and unit tests with Jest and React Testing Library. Includes an extended exercise building two application features. See how outside-in TDD leads to a thorough test suite, better regression safety, and a faster development speed.

How should we decide what kinds of tests to write for our React applications, and how many of each kind? How can we write a test suite that gives us confidence rather than just giving us busywork? Instead of tests slowing down our development, could they actually help us go faster?

Outside-In React Development tackles these questions by applying the practice of outside-in test-driven development (TDD) to React applications. It explains the problems that agile software development solves, the key role that test-driven development plays, and the way outside-intest-driven development helps end-to-end tests and unit tests to work together.

The main part of the book is an extended exercise building a React front-end application from scratch using outside-in TDD. You’ll learn:

• How and why to get your app tested on CI and automatically deploying before the first feature is written
• How to use the two-level TDD loop to stay laser-focused on building out one user-deliverable feature to completion
• How to write tests that provide maximum safety with minimum ongoing cost by testing the interface instead of the implementation
• How to get thorough coverage of edge cases while keeping your test suite fast