We have a few flakes in our tests, and there are many awesome improvements in Jest 23.

For instance, after having tracked a weird expect(something).toBeTruthy() random test error, after I upgraded locally to jest 23 the error immediately got clearer and started to show me the exact line that was failing.

The new --detectOpenHandles option seems also like a great things to help us improve and deflake our tests, by allowing us to track and fix the async calls we left out running in our tests and are likely the cause of some of our random failures.

NOT upgrading right now to not risk breaking things before Jenkins World demos. Trying this locally upgrades also a bunch of other things like babel to 7+. So better do this > next Wednesday .