In this kata author used old method to create ref in react(https://stackoverflow.com/questions/43873511/deprecation-warning-using-this-refs). I passed tests only because I saw test preparations and used console.log.
Some problems you may have with global function unshakle.
Good luck and have fun

this app use node 8.1.3 which doesn't support private methods(
you should use another approach for this purpose