With React Native, you can develop iOS and Android apps at the same time. This book covers learning React Native through a variety of examples, and further covers how to distribute your app to the market.
It also contains contents that can be used in practice, such as how to use Typescript.
You can learn to React with the test code from the book. First, you can learn the basics of React and make a simple app and then learn how to add the test code for it.
Lastly, you can learn TDD that you write the test code first and then write the app code after it.