Jest

adopt

Updated to "adopt".

Revisions:

assess | March 2017

Jest is a javascript testing framework by facebook to test javascript code and react applications / components.

We started using Jest (and watchmen) instead of Karma because it:

  • gives us integrated mocking library
  • gives us integrated support for testing "promises"
  • gives us integrated code coverage report
  • automatically runs tests related to changed files (instead of all tests)
  • gives us parallel test execution
  • gives us snapshot testing for react components

It is easy to set up. And even if you have a running setup with karma/chai you can easily replace karma with jest. With a small workaround, chai and jest test matchers work fine together.