Write tests. Not too many. Mostly integration.

— Guillermo ▲ (@rauchg) December 10, 2016

Whatever your approach to tests is - testing pyramid¹ or testing trophy² - you know that you need to write integration tests. In this post I’m going to show how to setup integration tests for React Native project.

In my project we keep files and their tests next to each other.

src
├─ hashing.js
└─ hashing.spec.js

I wanted a quick way to run tests for currently open file regardless which one of the pair is opened. I accomplished this by adding tasks.json to my project.

I work on React Native app and it’s important to do as little as possible at app start to reduce the time user has to wait before he can interact with the app. One of the things that helped to reduce wait time was switching from importing JavaScript modules at the top of the file to requiring modules in the functions that actully use them. But the challenge now is to prevent unwanted imports from appearing again.