As part of our move to continuous integration, we need a unit testing framework, in order to support our emerging Test-Driven-Development practice. By writing unit tests, we increase the confidence in our code and our build pipeline, and limit the number of issues when we make a code change.
Jest is Facebook's JavaScript unit testing framework. It is easy to use, with a "zero configuration" experience. It uses parallelization to increase the speed of your tests, and sandboxes them to minimize side-effects. It also contains common features that we like to see out of our unit testing frameworks: coverage reporting, mocks, etc. Finally, it integrates deeply with our React.js UI code.
Jest is used in all of our starter kits and reference architecture applications. We have very little configuration in the package.json, and only use it to enable the coverage report and to blacklist the node_modules folder, to increase test speed.
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